问题 选择题

如图所示,在加速向右运动的车厢中,一人用力向前推车厢(人与车厢始终保持相对静止),则下列说法中正确的是(        )

A.人对车厢的作用力做正功

B.车厢对人做负功

C.车厢对人做正功

D.车厢对人不做功

答案

答案:C

题目分析:在加速向右运动的车厢中,根据牛顿第二定律可知人受到的车厢对人的合外力水平向右,人的位移水平向右,所以车厢对人做正功。

故选C

点评:此题涉及到牛顿第二定律的应用和力的作用的相互性,注意车厢对人的作用力不止一个,车厢对人的力是这些力的合外力,不要认为车厢对人的作用力向后。

阅读理解

D

During the twentieth century there has been a great change in the lives of women. A woman marrying at the end of the nineteenth century would probably have seven or eight children, of whom four or five lived till they were five years old and up. By the time the youngest was fifteen, the mother would have been in her early fifties and would expect to live a further twenty years, during which chance and health made it unusual for her to get paid work. Today women marry younger and have fewer children. Usually a woman’s youngest child will be fifteen when she is forty-five and can be expected to live another thirty-five years and is likely to take paid work until sixty.

This important change in women’s life has only recently begun to have its full effect on women economic (经济的) position. Even a few years ago most girls left school and took a full-time job. However, when they married their school-leaving age is sixteen. Many girls stay at school after that age, and though women marry younger, more married women stay at work at least until shortly before their first child is born. Very many more afterwards return to fuller part-time work. Such changes have led to a new relationship in marriage (婚姻), with the husband accepting a greater share of the duties and satisfactions of family life.

71.We are told that in a family about 1900________.

A.few children died before they were five

B.seven or eight children lived to be more than five

C.the youngest child would be fifteen

D.four or five children died when they were five

72.One reason why the woman of today may take a job is that she______.

A.is younger when her children are old enough to look after themselves

B.does not like children herself

C.needn’t worry about food for her children

D.can be free from family duties when she reaches sixty

73.Many girls are now likely to_______.

A.give up their jobs for good after they are married

B.leave school as soon as they can

C.marry so that they can get a job

D.continue working until they are going to have a baby

74.According to the passage, it is now quite usual for women to _______.

A.stay at home after leaving school

B.marry men younger than themselves

C.start working again in life

D.marry while still at school

75.Now a husband probably_________.

A.plays a greater part in looking after children

B.helps his wife by doing much of the housework

C.feels dissatisfied with his part in the family

D.takes a part-time job so that he can help in the home

单项选择题