问题 选择题

如图所示的电路中,电源电压保持不变。闭合电键S后,电路正常工作。过了一会儿,两个电表中只有一个电表的示数变大。灯L和电阻R中的一个可能出现了故障。①若灯L发光,则故障是       ;②若灯L不发光,则故障是         

答案

电阻R短路  电阻R断路

题目分析:本题是灯与电阻的串联电路,电压表测电阻两端电压,电流表测的是串联电流。串联电路中电流只有一条路径,如果一个用电器断开,所有用电器都不能工作。若灯L发光,说明电路中有电流,灯泡正常,只有可能是电阻R短路,相当于导线,电阻为零,电阻两端电压为零。若灯L不发光,电路可能是断路,也可能是灯L短路,若灯L短路,则电流表和电压表示数都会变大,所以灯L不短路;若灯L断路,则电路中没有电流,电阻R两端也没有电压,不符合题意;若电阻R断路,电路中没有电流,电流表示数减小,但电压表正、负接线柱分别能与电源的正负极相连,所以电压表仍有示数,且等于电源电压,所以电压表示数增大,符合题意。

阅读理解

B

Would you eat a ready meal from the fridge rather than cook by yourself? Have you been doing Internet shopping rather than going to the stores? What can't you be bothered to do?

A study into how lazy British people are has found more than half of the adults are so idle (懒散的) that they'd catch the lift rather than climb two flights of stairs.

Just over 2000 people were quizzed by independent researchers at Nuffield Health, Britain's largest health center. The results were extremely surprising.

About one in six people questioned said if their remote control was broken, they would continue watching the same channel rather than get up.

More than one third of those questioned said they would not run to catch a bus. Worryingly, of the 654 respondents with children, 64% said they were often too tired to play with them.

This led the report to conclude that it's no wonder that one in six children in the UK are classified as obese (very fat) before they start school.

Dr Sarah Dauncey, medical director of Nuffield Health, said, “People need to get fitter, not just for their own sake, but for the sake of their families, friends and evidently their pets too.”

“If we don't start to take control of this problem, a whole generation will become too unfit to perform even the most fundamental tasks.”

And Scotland's largest city, Glasgow, was shamed as the most idle city in the UK, with 75% questioned admitting they do not get enough exercise, followed closely by Birmingham and Southampton, both with 67%.

The results bring serious challenges for the National Health Service, where obesity-related illnesses such as heart disease and cancer have been on a steady increase for the past 40 years and are costing billions of pounds every year.

60.How many people questioned don't play with their children?

A.1280.   B.More than 333.     C.654.    D.About 420.

61.The study leads us to believe that      .

A.the pets in the UK will be in trouble if their owners keep their way of life

B.Glasgow people feel ashamed because they don't get enough exercise

C.British people are the laziest around the world

D.five sixths of the British children are healthy

62.How does the author convince the readers?

A.By presenting the results of a study.                 B.By providing answers to questions.

C.By interviewing some experts.                            D.By telling a story.

63.What is the passage mainly about?

A.A study of British people's laziness.                 B.A study of British people's lifestyles.

C.The health service in the UK.                       D.The obesity problem in the UK.

单项选择题 B1型题