问题 选择题

下列说法中正确的是(  )

A.干燥的木棒是导体

B.对人体来说,不高36V的电压是安全电压

C.铜导线比铝导线的电阻小

D.用电器的电功率越大,消耗的电能越多

答案

A、不善于导电的物体叫绝缘体,干燥的木棒是绝缘体.不合题意.

B、对人体来说,不高于36V的电压是安全电压.符合题意.

C、导体的长度、横截面积也影响电阻大小,这时只说明材料不同,长度、横截面积不知道,因此不能得出铜导线比铝导线的电阻小.不合题意.

D、由电功公式W=Pt知,电功率大,但不知道时间,不能判断电能多少.不合题意.

故选B.

阅读理解

阅读理解。

    YOU may feel curious about students in other countries: Do they also have so much homework? What do they do in their spare time?

   On April 8, a report came out on the lives of high school students in China, Japan, South Korea and the US. It surveyed around 6,200 students from the four countries last year. You will find the answers to many of your questions in this report.

Who studies hardest?

    Chinese students spend the most time studying. Nearly half of Chinese students spend more than two

hours on their homework every day. That's much more than students of the US (26.4%), Japan (8.2%)

and South Korea (5.2%).

Who sleeps most often in class?

    Japanese students fall asleep in class most often. About 45% of them said they sometimes doze off in

class. In South Korea, it's 32%; in the US, 21%; and 5% in China.

South Korean students don't like taking notes. About 70% said they write down what the teacher says in

class, many fewer than in Japan (93%), China (90%) and the US (89%).

Who is the most distracted (分心的)?

    American students are the most active in class, but also the most distracted: 64.2% said they chat with

friends in class; 46.9% said they eat snacks in class; and 38.9% said they send e-mails or read unrelated (无关的) books in class.

What do they do after school?

   In their spare time, most Chinese students study or surf the Internet. Most American students hang out

with their friends. Most Japanese students do physical exercises. Most Korean students watch TV.

1. The report is about ___________.

A. the countries    

B. the subjects    

C. the students' lives  

D. the high schools

2. What country isn't mentioned in the report?

A. The US      

B. South Korea    

C .Japan        

D. India

3. _______ of the Chinese students spend more than two hours on their homework.

A. 26.4 %        

B. 8.2 %          

C. 5.2 %        

D. 48.6 %

4. What of the following sentences is Not true?

A .The survey from the four countries was made last year.

B. Most Japanese students do physical exercises after school.

C .About half of the American students chat with freinds in class

D. The students in South Korean don't like taking notes in class.

单项选择题