问题 单项选择题

我国的“神舟”号飞船的发射时间基本七都是选择在凌晨和子夜,那么,神舟飞船为什么选择在夜晚发射呢( )

A.白天有太阳光照射,容易使火箭升温

B.白天电磁波干扰强烈

C.在漆黑的夜空中,喷射着火焰向太空飞行的载有飞船的火箭非常显眼和突出,地面的光学跟踪测量设备易于捕捉到跟踪目标

D.夜晚天气变化小,有利于火箭发射

答案

参考答案:C

解析: 载人航天飞船的发射时间是经过航天专家综合多种因素严密计算的结果而确定的,一般都选在夜晚或凌晨发射,由于喷射的火焰特别显眼,地面的光学跟踪测量设备容易跟踪目标;而阳光强烈的白天就不利于地面光学跟踪设备对飞船的跟踪。故选C。

判断题
单项选择题

Many parents complain that their teenage children are rebelling. They greet their children’s teenage with needless dread. While teenagers may assault us with heavy-metal music, wear strange clothes, have strange hair styles, and spend all their time dating or meeting friends, such behavior scarcely adds up to full-scale revolt.

Take a good look at the present rebellion. It seems that teenagers are all taking the same way of showing that they disagree with their parents. Instead of striking out boldly on their wings, most of them are clutching at one another’s hands for reassurance. Their reason for thinking or acting in thus-and-such a way is that the crowd is doing it. It has become harder and harder for a teenager to stand up against the popularity wave and to go his or her own way. They have come out of their cocoon—into a larger cocoon.

Teenage rebellion, according to psychologist Laurence Steinberg, coauthor of You and Your Adolescent, has been greatly overstated. Many other psychologists agree. The idea that teenagers inevitably rebel is a myth that has the potential for great family harm. This notion can damage communication during this critical time for parents to influence youngsters.

Still adolescence is often a trying time of transition for child and parent. Teenagers need to establish themselves as individuals—in their own minds and in the eyes of others. This search isn’t about rebellion: it’s about becoming a person of one’s own. " Teenagers ought to be growing away from their parents and learning to stand on their own two feet, " says Steinberg.

Here is one way parents can help: don’t stereotype. " Parents who expect teenage rebellion may actually stir it up, " says Kenneth I. Howard, a member of a research team that collected survey data on more than 20,000 teenagers over a 28-year period.

Howard cautions parents not to resort to suppression at the first sight of adolescent independence, fearful that giving in even slightly now means drugs cannot be far behind. When parents overreact, teenagers assert themselves more, parents clamp down harder, and a full-scale blowup results.

In fact, psychologists say that there is no inevitable pattern to teenage behavior, and no such creature as a typical teenager. Your teenager is now larger, per, older and smarter than before, with an additional supply of hormone raging through the bloodstream. But he or she is still the same human being you have lived with since birth. Given a chance, your son or daughter will continue to behave in ways you have established.

" A larger cocoon " as mentioned in paragraph 2 refers to the situation that()

A.teenagers disagree with their parents

B. teenagers want to be independent

C. teenagers cannot escape from the popularity wave

D. teenagers need support from their fellow teenagers