一蹦极运动员身系弹性蹦极绳从水面上方的高台下落,到最低点时距水面还有数米距离。假

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问题:

一蹦极运动员身系弹性蹦极绳从水面上方的高台下落,到最低点时距水面还有数米距   离。假定空气阻力可忽略,运动员可视为质点,下列说法正确的是(   )

A.蹦极绳张紧后的下落过程中,运动员的加速度先增大后减小

B.运动员从下落到达最低点前,速度先增大后减小

C.蹦极过程中,运动员、地球和蹦极绳所组成的系统机械能不守恒

D.蹦极过程中,重力势能的改变量与弹性势能的改变量总是相等

考点:牛顿第二定律
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脱式计算。
(1)689-(312+258)(2)680-546+219
(3)370-8×8(4)241+72÷9
题型:选择题

阅读理解

      What do working mothers worry about the most? It's the kids of course. Whatever the setting, the

question I get asked the most is "Will the kids be alright?" It's made me realize that we tend to look at the

glass half-empty rather than half-filled when it comes to mixing work and family. We forget about all the

benefits that we bring to our children when we work - and I'm not talking about the obvious financial

benefits, although these of course shouldn't be taken for granted.

     About a year ago I remember getting a call from the school just as I was pulling up to the house after

having driven 20 minutes to the school and 20 minutes back. "Mrs. Brown Quinn, your son asked us to

call. He forgot his sports clothes. Can you come back to the school and drop them off?" I was exasperated(恼火)! I had already spent 40 minutes in aggressive weekday morning traffic. I replied, "Sorry, I'm

working at the moment. I'm afraid my son needs to learn to be organized."

     Being a good parent requires delivering tough love sometimes. Kids need to learn to be independent.

It can be a cruel and competitive world out there. Seeking   interests, including business, outside of your

kids, can give you that extra idea that you need not care for your kids with attention. This benefit of

working isn't always immediately evident.

     It wasn't until our daughter went away to college that she realized why we had raised her in the way

that we did. "Mom, I can't believe how so many of my friends struggle to manage things on their own.

They are constantly calling their parents for help." You'll love that moment! After all those years of

complaining about why you don't do this or why you don't give them that, your kids realize that tough

love has made them better people.

1. The author refused to drop off her son's sports clothes because ______.

A. she was caught in heavy traffic

B. she was busy working

C. she thought her son was lying

D. she wanted her son to be organized

2. How can kids become better people according to the author?

A. By giving them all your attention.

B. By giving them freedom to do things on their own.

C. By showing them your deep love.

D. By giving them tough love.

3. The daughter's attitude towards the author is ______ when she grows up.

A. surprised

B. caring

C. understanding

D. disappointed

4. The purpose of the author is to ______.

A. throw light on a special benefit of working

B. advise us to mix work and family

C. argue for working mothers

D. describe her own experience in raising children

题型:选择题

肺炎球菌肺炎()

A.咯血颜色鲜红

B.铁锈色血痰

C.砖红色胶冻样黏痰

D.粉红色乳样痰

E.粉红色浆液性泡沫样痰

题型:选择题

一个三相对称负荷,每相电阻R=8ΩXL=6Ω,接成Y形,电源电压380V,则线电流()。

A.15.7A

B.22A

C.27.1A

D.38A

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