问题 填空题

如图所示,固定圆弧轨道弧AB所含度数小于5°,末端切线水平.两个相同的小球a、b分别从轨道的顶端和正中由静止开始下滑,比较它们到达轨道底端所用的时间和动能:ta______tb,Ea______2Eb

答案

两小球的运动都可看作简谐运动的一部分,时间都等于四分之一周期,而周期与振幅无关,所以ta=tb;从图中可以看出b小球的下落高度小于a小球下落高度的一半,所以Ea>2Eb

故答案为:=,>

阅读理解

阅读理解。

     If you don't keep yourself warm enough, winter can be a time of illness.

     During the winter months, people easily get colds and flu (流感). Many think they are the same, but

these two illnesses are different.

     Colds can stay with you for up to a week. You will have a running nose, sore throat, headache, cough

and a fever.

     Flu is more serious. You will feel sick very quickly. You will have a fever and a headache. Your body

will hurt and become weak. This could last for up to four weeks. 

     Is there any way to keep yourself away from colds and flu? Staying clear of people with colds or flu

may work.

     Try not to touch (触摸) your nose or eyes if you have been close to someone who has a cold. Wash

your hands, especially after cleaning your nose.

     Going out with wet hair can also give you a cold!

     If you catch a cold or flu, go to bed and rest. Doing this will help you get better. Drink lots of water.

Stay in a warm, well-aired room. If you have a headache, or your muscles hurt, take some medicine.

1. 阅读上面的短文,根据短文内容帮助Mary完成下面的一封信。

Dear Mom and Dad, 

     How's everything going?

     I'm having great fun at winter camp. But for the past two days, I'm not feeling very well. I don't know

what's wrong. Maybe I have ____ a cold. I have a ____ nose and ____ throat. Last night I couldn't sleep

because I had a _____, ____ and a slight ____. But don't worry. I've been to the doctor's. The doctor told

me that it was not ____, which would otherwise be more ____. He advised me to ____ lots of water, lie

down and ____ for a few days. He said I would get well in a week. Okay, so much for now.  

     Take good care of yourselves, too.

                                                                                                                                             Love,

                                                                                                                                             Mary

2. 假设你是Mary的朋友Tina. 得知她生病的消息后,你很着急,立刻发一封e-mail,给她提一些建议

(三至五条,可参考短文,字数100字左右)。

                                                                                                                                                         

                                                                                                                                                         

                                                                                                                                                         

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