问题 选择题
求如图所示的交变电流的有效值,其中每个周期的后半周期的图象为半个周期的正弦曲线(   )

A.5A

B.5A

C.5/2A

D./2A

答案

答案:C

单项选择题 A2型题
阅读理解

阅读短文,根据要求完成下面各小题。

     In May 2011, Gao Xiaosong, a Chinese musician, was caught in a car accident. When the police asked

him to take a breath alcohol test (酒精呼气测试), the result showed that he had drunk too much wine.

Because of that, he is now in prison (监狱) and can't be allowed to drive cars in China for five years.

     Nowadays, cars are very important in people's life. More and more cars are going into Chinese families.

However, lots of car accidents take place and many people are hurt or killed every year. According to a police

survey, 3 there are a lot of drivers driving after drinking. And the number of drunken driving is still large.

     After drinking, a driver can't control himself or his car. In some cases (案例), some drivers even drove

into rivers or houses after they drank.

     As it is so dangerous, there is no excuse for drunken driving. Remember the following three rules when

driving.

·Never drive after drinking.

·Never let anyone drive after drinking.

·4 Never give alcohol to anyone who would drive later.

     If all of us can keep these rules in mind, there will be fewer car accidents, fewer people will be

heart-broken. For the safety of ourselves and for the happiness of our families,we must remember: No

driving after drinking!

1. How many years can't Gao Xiaosong be allowed to drive?

   ________________________________________________________________________

2. Why can't people drive after drinking? 

   ________________________________________________________________________

   将短文中画线部分的句子译成汉语。

3.  ________________________________________________________________________  

4.  ________________________________________________________________________

5.   请给短文拟一个适当的标题。

   ________________________________________________________________________