问题 选择题
3A的直流电通过电阻R时,t时间内产生的热量为Q;现让一交流电通过电阻R,若2t时间内产生的热量为Q,则该交流电流的有效值和最大值分别为(  )

A.I=3/2A,Im=3A

B.I有=3A,I=3A

C.I有= A,I A

D.I3A,Im=6A

答案

答案:A

填空题
阅读理解

阅读理解。

     Having friends may well keep you healthier and help you deal with stress better. Some studies show that

people with close friends have a greater ability to fight diseases than people who are alone.

     Make friendship a priority. Find the time to be with friends even if it means letting the lawn go unmowed

or the dishes unwashed for a while. When you can't get together, use the phone to keep in touch.

     Open up to close friends. Maintaining a deep friendship requires a level of "heartfelt" intimacy (亲密).

Don't be afraid to express your inner fears and disappointments. Listen to your friends when they have

problems, but offer advice only when it's wanted. Help raise friends' self-esteem (自尊) when they are shaken

by a job loss, or other such events.

     Have different friends for different activities, such as going to the movies, singing in a choir, and joining

in a bowling league.

     Don't wait for a friend to ask a favor. When a friend has the flu, offer to go to the store or drive his or her

children to their after-school activities.

     Never take a friendship for granted. Like a good marriage, friendship needs care and patience. Become a

joiner. Find a group that matches your interests.

     Talk to strangers. Conversations started in museums, laundry rooms, or bookstores can lead to firm

friendship.

     Enroll in an adult-education course. A classroom is an ideal place to meet others with similar interests.

1. People with close friends have a _____ ability to fight diseases than people who are alone.

A. less

B. greater

C. poorer

D. little

2. According to the passage, you'd better offer advice to your friends _____.

A. at any moment

B. only when they are happy

C. only when they want it

D. only when you are glad

3. What should we do to have friends according to the author?

A. Make friendship a priority.

B. Open up to close friends.

C. Never take a friendship for granted.

D. All of the above.

4. Which of the following is TRUE according to the passage?

A. You should have different friends for the same activities.

B. You should wait for a friend to ask a favor.

C. You should avoid talking with strangers in museums, laundry rooms, or bookstores.

D. You should never take a friendship for granted.

5. The underlined word "Enroll" in the last paragraph means _____.

A. Give

B. Join

C. Get

D. Catch