问题 问答题

电流表使用时必须注意:

(1)使用前,要检查表的指针是否对准______.

(2)电流表必须______联在所测电路中.

(3)把电流表接入电路之前,应先估计电路中电流的大小,若不清楚,可先选用______量程把表接入电路,若表的指针不超过量程时再接牢.若指示值偏小,最好改用______进行测量.

(4)应使所测电流从表的______接线柱流入,从______接线柱流出.

(5)绝对不允许不经过______而将表的两个接线柱直接连接到电源两极上.

答案

①在使用电流表前,需要先检查电流表的指针是否对准零刻线;

②电流表必须串联在被测电路中;

③电流表有两个量程,当不确定被测电流大小时,应先选用较大量程进行试触,如果指针偏转角度较小,再改用较小量程进行测量;

④电流必须是从电流表的正接线柱流入;

⑤绝对不允许不经过用电器而将电流表直接接在电源的两极上.

故答案为:①零刻线;②串;③较大,较小量程;④“+”,“-”;⑤用电器.

单项选择题 A2型题
阅读理解

阅读理解

     My dad, Greg Newman, had wanted to be a race  car driver, but things didn't work out for him.So

I guess having a son who could become a race car driver was the next best thing.Don't get me

wrong-Dad didn't push me into racing.In fact, when I was about 10 years old, my dad was afraid that

driving a car wasn't my dream.So he took the racing away from me.I wasn't very happy with that decision.It wasn't long before Dad realized that racing was what I loved.

     At four, Dad bought me my first Quarter Midget (袖珍赛车)  and that's really where it started for us.

Back then, Dad coached me.He would stick out (伸出) his footin the path of the race car, and then tell

me to exactly hit his foot.By repeating this again and again, Dad believed that I would be faster and

sharper on the race track.

     Dad worked really long hours at his car repair business to make money so that I could race each

weekend.I can remember that every night before he turned off the lights in the garage, Dad would tell

me:"Don't forget to kiss your race car good night." He was trying to teach me that if I show respect, it's

returned.He wanted me to show thankfulness and respect for my race car and for all the hard work that

we and many others had put into the dream.

     My dad, my mom and my sister gave up a lot of things to help me race.For us, there was no better

moment than winning the 50th running of the Daytona 500 in 2008.That evening in February 2008, I

knew I had gotten a good push.I could hear the excitement.My father couldn't speak a word, and when

he got to  Victory Lane (车道), he nearly knocked me over and  gave me such a big hug.

1. Why did Greg Newman stop his son to race when his son was 10 years old?

A. Because he thought racing was dangerous.

B. Because he worried that his son didn't like racing.

C. Because he didn't want his son to fail like he did.

D. Because he couldn't afford the money.

2. Greg Newman did all the following things to support his son's dream EXCEPT________.

A. training his son to race

B. working hard to make money

C. buying his son a mini racing car

D. changing his job as a race car driver

3. Why did Greg Newman let his son hit his foot?

A. To improve his son's skill.  

B. To help his son to be braver.

C. To have fun with his son.      

D. To make his son more careful.

4. Greg Newman asked his son to kiss his race car good night to________.

A. get help from his family

B. treat the race car as a person

C. feel grateful that he could follow his dream

D. develop a close relationship with his race car

5. In the 50th running of the Daytona 500, Greg Newman couldn't say anything because he was______.

A. disappointed  

B. surprised  

C. sad    

D. excited