某同学骑自行车作匀速直线运动，在4s内通过40m的路程，那么他在前2s内的速度是

根据行为改变阶段的模式，对于问题尚无了解的患者，应采取的措施是（）。

A.提供信息，提高认识

B.提高认识，激发动机

C.提供方法，鼓励尝试

D.支持鼓励，加以强化

E.不断强化，预防复发

The Need for Holidays

You’ve no doubt heard people say how much they “need” a holiday，when what they really mean is that they want one．Certainly，people working under pressure feel a very strong desire to escape from work and become less tight during their holidays，and experience a changed environment. For this reason, holidays away from home are now seen by most people as necessary to their quality life. However, work for many people today are office work and mental, rather than physical tasks. These people may seek much more energy taking activities while on holiday, rather than simply lying on a beach.

Once people become used to going on holiday, taking holidays becomes a habit. Even in a recession(经济萧条时期), for many people the holiday is one of the last things to be given up, and indeed many workers have chosen to spend some of their last pay when being laid off on a holiday, perhaps to give themselves a "lift” before facing a gloomy(暗淡的)future.

Perhaps we don't like to admit it, but most of us also enjoy showing off about the places we have been to, and the lovely tans：dark skins we have got. The idea of tanning, however, is becoming less attractive than it was. So many tourists are now able to afford holidays in the sun that tans have become quite common；and although we join a tan together with health(and it is true that a certain amount of sunshine gives us a feeling of being healthy), it has been fully shown that sunshine，especially when received over a short, focused period of time, results in high danger of skin problems, as well as drying out one's skin and leading to more lines on your face later in life.

57．More and more people choose to have holidays because they ________.

A. hate working indoors all the time                      B. want to get away from work

C. love enjoying the beauties of nature                      D. become rich and want a better life

58．From this passage we learned that some people can not live without ______．

A. a tan            B. a job           C. a pay       D. a holiday

59．A holiday may __________ when one has to face some difficulties in life．

A. cheer someone up                                          B. help someone find a job

C. be the last thing to be given up                             D. bring good luck to someone

60．At the end of the passage the writer tries to tell the reader ________.

A. the importance of getting sunshine                        B. the bad effect of being on holiday

C. the result of getting sun tanned                             D. the healthy look of being tanned

高度超过（）米的脚手架必须设置安全网。

A、3

B、4

C、4.5

D、5

启用备用管线，为了不影响正常生产，管道阀门切换的不正确操作方法是（）。

A.切换过程派人监视压力参数

B.切换前先检查备用管线完好

C.先关闭原管线阀门，后渐打开备用管线阀门

D.渐打开备用管线阀门，同时渐关闭原管线阀门，直至完全切换

有毒蜜粉源植物？