问题 问答题

用打点计时器测定物体的速度,当使用的电源频率高于50Hz时,如果仍按50Hz来计算,则测得的速度将比真实值______(偏大、偏小、无影响).

答案

打点周期与交流电的周期相同,T=

1
f
=0.02s,当电源频率高于50Hz时,实际打点周期将变小,而进行计算时,仍然用0.02s,因此测出的速度数值将比物体的真实数偏小.

故答案为:偏小

阅读理解

Being healthy means taking care of yourself physically and mentally. Here are some of my best tips on how to do both:

Break a bad habit.

You don’t really “break” habits. __小题1:__. So if your problem is that you eat too much when you get home from work, find something new to do that is incompatible(不能共存的)with what you usually do. You can’t walk around the track at the school and pig out in your kitchen at the same time.

Grow your marriage.

__小题2:__. It’s always a give-and-take, always requires work. It’s as if you planted a garden and came back six months later─you wouldn’t even be able to find it. __小题3:__.

Beat stress.

My dog, Maggie, is the best anti-stress tool I have. A few minutes petting, scratching or playing with her, and __小题4:__. Exercise also helps. Just about every day, I’m on the tennis court. It’s a great workout, and if I don’t have that, I don’t cope as well, sleep as well or think as well.

Refocus your anger.

Expressing your anger is just not that good an idea. You say things you don’t mean. __小题5:__. When you do that, you’re a problem solver.

Don’t medicate(掺入药) with food.

It never, ever works. You’re denying your issue by eating your way through it, instead of saying, “Hey, I’ve got a problem.”

A.You replace the unwanted behavior with something that prevents you from doing it and that doesn’t have unhealthy side effects.

B.I’ll feel easy.

C.If there is a problem, you needn’t deal with it immediately.

D.You have to tend it, feed it, weed it, and deal with the problems.E. Instead, recognize that anger is usually a symptom of hurt, fear or frustration, and deal with the causes rather than blow up.

F. Relationships are negotiated(协商), and the negotiation never stops.

G. You do something without any good effect on your health during the time when you usually do something harmful to your body.

选择题