在波的传播方向上,两质点a、b相距3.5m,已知t=0时刻,a位于波峰,b恰好在

题型:选择题

问题:

在波的传播方向上,两质点ab相距3.5m,已知t=0时刻,位于波峰,b恰好在平衡位置,除a点外,ab间还有一个波峰;t=0.1s时刻,a位于平衡位置。则波的传播速度可能是(     )

A.14 m/s

B.15 m/s

C.21 m/s

D.30 m/s

考点:波长、频率和波速
题型:选择题

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

Why Exercise Is Cool?

1. Exercise Strengthens Muscles

Did you ever do a push-up or swing across the monkey bars at the playground?    小题1:   By using your muscles to do powerful things, you can make them stronger. For older teens and adults, this kind of workout can make muscles bigger, too.

2.    小题2: 

Can you touch your toes easily without yelling ouch? Most kids are pretty flexible, which means that they can bend and stretch their bodies without much trouble. Being flexible is having “full range of motion,” which means you can move your arms and legs freely without feeling tightness or pain.

3. Exercise Keeps the Balance

   小题3:  Your body needs a certain amount of calories every day just to function, breathe, walk around, and do all the basic stuff.    小题4:   If you’re not very active, your body won’t need as many calories.

Whatever your calorie need is, if you eat enough to meet that need, your body weight will stay about the same. If you eat more calories than your body needs, it may be stored as extra fat.

4. Exercise Makes You Feel Good

It feels good to have a strong, flexible body that can do all the activities you enjoy—like running, jumping, and playing with your friends. It’s also fun to be good at something, like scoring a basket, hitting a home run, or perfecting a dive.

But you may not know that exercising can actually put you in a better mood.    小题5:   It’s just another reason why exercise is cool!

A.So you want to do some aerobic (有氧的) exercise right now?

B.Food gives your body fuel in the form of calories, which are a kind of energy.

C.When you exercise, your brain releases a chemical, which may make you feel happier.

D.Those are exercises that can build strength.E. Exercise Makes You Flexible

F. Exercise Makes Your Heart Happy

G. But if you’re active, your body needs an extra measure of calories or energy.

题型:选择题

开放性损伤早期防止感染的最根本的手段是:()。

A.尽早清创

B.彻底清创

C.应用抗生素

D.放置引流

E.清热解毒药物的应用

题型:选择题

治疗气滞血瘀型经行浮肿的最佳方剂是:()

A.血府逐瘀汤

B.少腹逐瘀汤

C.八物汤

D.苓桂术甘汤

E.白术散

题型:选择题

隔离开关修前检查和试验的项目()。

A.隔离开关在停电前,带负荷情况下的红外测温

B.隔离开关主回路电阻测量

C.都做

题型:选择题

随着时代的进步,新型的、民主的家庭气氛和父母子女关系还在形成,但随孩子的自我意识逐渐增强,很多孩子对父母的教诲听不进或当作“耳边风”,家长感到家庭教育力不从心。教师应该()。

A.放弃对家长配合自己工作的期望

B.督促家长,让家长成为自己的“助教”

C.尊重家长,树立家长的威信,从而一起做好教育工作

D.在孩子面前嘲笑这些家长

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