1.(新课标卷)电源的效率定义为外电路电阻消耗的功率与电源的总功率之比.在测

电源电动势和内电阻的实验中得到的实验图线如图所示，图中U为路端电压，I为干路

电流，a、b为图线上的两点，相应状态下电源的效率分别为、.由图可知、

的值分别为

　　 A、、　　 B、、　　 C、、　　 D、、

答案：D

解析：电源效率，E为电源的总电压(即电动势)，根据图象可知U_a=

U_b=，所以选项D正确。

100．The whole passage centers around ________.

　A. knowing oneself in looking for a job

　B. developing one’s abilities useful in school

　C. gaining much knowledge by working hard at school

　D. choosing a career according to what one is skilled in

99．If a student’s school record is not good, according to the passage, he________ .

　A. may do well in his future work

　B. won’t be able to find a suitable job

　C. may be a complete failure in the future

　D. will regret not having worked harder at school

98．In the writer’s opinion, for a student to have a part - time job is probably ________.

　A. a good way to find out his weak points

　B. one of the best ways of earning extra money

　C. of great use for his work in the future

　D. a waste of time he could have spent on study

97．The first paragraph of the passage is mainly about ________.

　A. the indirect value of school work

　B. the importance of being good at all subjects

　C. knowing one’s strong or weak subjects at school

　D. using school performance to help to choose a career

96．The passage is mainly about ________.

　A. the memory system of persons

　B. a way of encoding and recalling

　C. the causes of absent - mindedness

　D. the impression of the environment on memory

No. 25

　What should you think about when you try to find your career? You are probably better at some school subjects than others, These may show strengths that you can use in your work. A boy who is good at mathematics can use that in engineering career. A girl who spells well and likes English may be good at office work. So it is important to know the subjects you do well in at school. On the other hand, you may not have any specially strong or weak subjects but your records show a general satisfactory standard. Although not all subjects can be used directly in a job, they may have indirect value.

　Your school may have taught you skills, such as typing or technical drawing, which you can use in your work. You may be good at mental work or cookery and look for a job where you can improve these skills.

　If you have had a part - time job on Saturday or in the summer, think what you gained from it. If nothing else, you may have learned how to get to work on time, to follow instructions and to get on with older workers. You may have learned to give correct change in a shop, for example. Just as important, you may become interested in a particular industry or career you see from the inside in a part - time job.

　Facing your weak points is also part of knowing yourself. You may be all thumbs when you handle tools; perhaps you are a poor speller or cannot add up a column of figures. It is bitter to face any weaknesses than to pretend they do not exist. Your school record, for instance, may not be too good, yet it is an important part of your background. You should not feel sorry about it but instead recognize that you will have a chance of a fresh start at work.

95．From the last paragraph we can learn that________.

　A. repetition might help improve our memory

　B. memory depends to a certain extent on the environment

　C. we’d better return to where we were if we forget things

　D. we should think about something else while doing one thing

94．Why can a note in the pocket hardly serve as a reminder? ________.

　A. It will easily get lost

　B. It is out of your sight

　C. It’s not clear enough for you to read

　D. It might get mixed up with other things

93．One possible reason why women have a little better memories than men is that________.

　A. they rely more on the environment

　B. they have a wider range of interests

　C. they have an unusual power of focusing their attention

　D. they are more interested in what’s happening around them

92．The writer of the passage thinks that encoding properly is very important because ________.

　A. it enables us to recall something from our memory

　B. it slows down the process of losing our memory

　C. it helps us understand our memory system better

　D. it helps us to get back to where we were