import numpy as np
from sklearn.linear_model import LinearRegression
import matplotlib.pyplot as plt

np.random.seed(42)

X1 = 2*np.random.rand(100,1)
X2 = 2*np.random.rand(100,2)
X = np.c_[X1,X2]
print("Input X shape: {}".format(X.shape))

y = 4*np.random.randn(100,1)
print("Input y shape: {}".format(y.shape))

reg = LinearRegression(fit_intercept=True)
reg.fit(X, y)

print("Intercept: {}\nEstimated coefficients: {}".format(reg.intercept_, reg.coef_))

# 预测
# X_new与X的维度应该一致,都是3列
X_new = np.array([[0,0,0],[2,1,2],[2,4,3]])
y_predict = reg.predict(X_new)
print("Predicted values:\n{}".format(y_predict))

#绘图
plt.plot(X, y, 'b.')
plt.plot(X_new, y_predict, 'r-')
plt.axis([0,2,0,15])
plt.show()

老师，如果我们的数据集没有办法分辨y和维度x是属于线性变化关系，也就是我们没办法提供类似y = a + bx的表达式，那么是不是我们就不应该使用简单线性回归去训练模型？因为很多时候在工作上，对于训练集里面的数据，我们是不太清楚维度与真实值之间的关系的（譬如：y=sales, x1=广告投入, x2=人力成本, x3=原材料成本）。我尝试了一下去算输入的X和y，结果很怪，绘图出来的分界线很差很怪，感觉它们不是线性关系，不应该用简单LR去做，麻烦老师纠正我的理解。

老师，这个连接条件是怎么选的？为啥是department_id这一列，是因为两个表中都有这一列吗？

老师，请问为什么第一个输出的是None，第二个才是添加后的a？谢谢

开启事务提交要怎么关闭？ 把cmd关了再开吗

资料中没有提供视频中的mybatiscodehelperpro插件。老师可否提供一下呢

老师我在尝试运行AdminServiceApplication时ide提示以下错误。。我反复检查了使用插件生成service, service impl以及Mapper部分的内容和老师的都是一样的。

根据下面的错误提示，我查了下configServiceImpl中是有@Service注解的，和老师的代码一样用的是Spring的@Service注解。

再下面有个Error creating bean with name 'com.alicp.jetcache.anno.config.JetCacheProxyConfiguration，我也查了确实正确添加了jetcache的依赖。。

不解为什么还会提示下面的错误。。

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.

2020-12-03 03:35:24.457  INFO 64804 --- [           main] c.a.alicloud.oss.OssApplicationListener  : 0 OSSClients will be shutdown soon

2020-12-03 03:35:24.571 ERROR 64804 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'configServiceImpl': Unsatisfied dependency expressed through field 'baseMapper'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.bjsxt.mapper.ConfigMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:643) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1422) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:895) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at com.bjsxt.AdminServiceApplication.main(AdminServiceApplication.java:20) [classes/:na]

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.bjsxt.mapper.ConfigMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1716) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1272) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

... 20 common frames omitted

2020-12-03 03:35:24.575  WARN 64804 --- [           main] o.s.boot.SpringApplication               : Unable to close ApplicationContext

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'applicationAvailability' defined in class path resource [org/springframework/boot/autoconfigure/availability/ApplicationAvailabilityAutoConfiguration.class]: BeanPostProcessor before instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.alicp.jetcache.anno.config.JetCacheProxyConfiguration': Initialization of bean failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry' available

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:512) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.event.AbstractApplicationEventMulticaster.retrieveApplicationListeners(AbstractApplicationEventMulticaster.java:245) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.event.AbstractApplicationEventMulticaster.getApplicationListeners(AbstractApplicationEventMulticaster.java:197) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:134) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:403) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:360) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:81) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:67) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.doClose(ServletWebServerApplicationContext.java:167) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:978) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:814) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:325) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]

at com.bjsxt.AdminServiceApplication.main(AdminServiceApplication.java:20) [classes/:na]

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.alicp.jetcache.anno.config.JetCacheProxyConfiguration': Initialization of bean failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry' available

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:603) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:409) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.aop.framework.autoproxy.BeanFactoryAdvisorRetrievalHelper.findAdvisorBeans(BeanFactoryAdvisorRetrievalHelper.java:91) ~[spring-aop-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findCandidateAdvisors(AbstractAdvisorAutoProxyCreator.java:109) ~[spring-aop-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator.findCandidateAdvisors(AnnotationAwareAspectJAutoProxyCreator.java:92) ~[spring-aop-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator.shouldSkip(AspectJAwareAdvisorAutoProxyCreator.java:101) ~[spring-aop-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessBeforeInstantiation(AbstractAutoProxyCreator.java:251) ~[spring-aop-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInstantiation(AbstractAutowireCapableBeanFactory.java:1141) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeforeInstantiation(AbstractAutowireCapableBeanFactory.java:1114) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:506) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

... 18 common frames omitted

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry' available

at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:814) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1282) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:297) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:276) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.context.annotation.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor.postProcessBeforeInitialization(ConfigurationClassPostProcessor.java:456) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:416) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1788) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]

... 40 common frames omitted

老师 这个nodemon 我也装上了 但是运行这个nodemon index.js出现的错误是什么意思呢

还有这些文件旁边的 UM是什么意思呢

那为什么我的浏览器不显示这些东西呀，我跟着老师一步步做的呀，其他的效果都一样唯独浏览器报错信息不老师少很多提示信息，比如提示多少行多少列出问题我就没有

老师，我是了一下，直接给某个列加上唯一性索引，不加唯一性约束他也不能重复添加相同数据，这种正常吗

为什么查不到我的MySQL呢，我按视频里弄的

用idea 网页啥也不显示咋回事啊老师，然后自带的那个软件也用不了，然后idea这个点那个谷歌的小图标也点不了，显示没有路径

老师可以给个xampp下载安装包嘛，这边官网的下载页面加载不出来

老师，我在写的时候为什么有个父元素的margin会影响子元素的位置呢，如下图所示（此时父元素里有个margin：0 auto，子元素居中了）：

去掉父元素的margin：0 auto后，该子元素不居中了

下面是我的源代码，麻烦老师看看

<script>
    var alt="";
    for (var i=1;i<=5;i++){ //代表行
        var blank="";
        for (var j=1;j<=5-i;j++){ //代表空格
            blank+=" ";
        }
        var star="";
        for (var s=1;s<=2*i-1;s++){
            star+="*";
        }
        alt+=blank+star+"<br/>";
    }
    document.write(alt);
</script>

老师为什么我的不是等腰三角形呀，那个blank哪也弄了空格了，我弄不出那个题的效果，老师帮忙看看吧

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.0/dist/css/bootstrap.min.css" integrity="sha384-9aIt2nRpC12Uk9gS9baDl411NQApFmC26EwAOH8WgZl5MYYxFfc+NcPb1dKGj7Sk" crossorigin="anonymous"><link rel="stylesheet" href="css/bootstrap.min.css">
    <link rel="stylesheet" href="css/练习专用.css">
</head>
<body>

    <div class="container"><div class="alert alert-primary" role="alert">
        A simple primary alert—check it out!
    </div>
        <div class="alert alert-secondary" role="alert">
            A simple secondary alert—check it out!
        </div>
        <div class="alert alert-success" role="alert">
            A simple success alert—check it out!
        </div>
        <div class="alert alert-danger" role="alert">
            A simple danger alert—check it out!
        </div>
        <div class="alert alert-warning" role="alert">
            A simple warning alert—check it out!
        </div>
        <div class="alert alert-info" role="alert">
            A simple info alert—check it out!
        </div>
        <div class="alert alert-light" role="alert">
            A simple light alert—check it out!
        </div>
        <div class="alert alert-dark" role="alert">
            A simple dark alert—check it out!
        </div>
    </div>

    <div class="alert alert-primary" role="alert">
        A simple primary alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>
    <div class="alert alert-secondary" role="alert">
        A simple secondary alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>
    <div class="alert alert-success" role="alert">
        A simple success alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>
    <div class="alert alert-danger" role="alert">
        A simple danger alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>
    <div class="alert alert-warning" role="alert">
        A simple warning alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>
    <div class="alert alert-info" role="alert">
        A simple info alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>
    <div class="alert alert-light" role="alert">
        A simple light alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>
    <div class="alert alert-dark" role="alert">
        A simple dark alert with<a href="#" class="alert-link">an example link</a>. Give it a click if you like.
    </div>

    <div class="container">
        <div class="alert alert-warning alert-dismissible fade show" role="alert">
            <strong>Holy guacamole!</strong> You should check in on some of those fields below.
            <button type="button" class="close" data-dismiss="alert" aria-label="Close">
                <span aria-hidden="true">&times;</span>
            </button>
        </div>
    </div>

    <script src="https://cdn.jsdelivr.net/npm/jquery@3.5.1/dist/jquery.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
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老师，我有两个问题想问下——1.这里面2:40里的呈现效果跟视频不一样，它占满了整个宽度。

                                                2.视频中3:40秒的时候呈现出来的效果，这边是一段空白。