如图所示，有M和N两颗质量相等的人造地球卫星，都环绕地球做匀速圆周运动．这两颗卫星相比较（　　）_百度知道
提问者采纳
A、由万有引力提供向心力： G
r ，解得： T=2π
，可知半径大的周期大，故M的周期大，故A错误．B、由万有引力提供向心力： G
，解得： v=
，可知半径大的线速度小，故M的线速度小，故B正确．C、由万有引力提供向心力： G
r ，解得： ω=
，可知半径大的角速度小，故M的角速度小，故C错误．D、卫星发射得越高，克服地球引力做功就越多，获得的机械能就越大，故M的机械能较大，故D正确．故选：BD．
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出门在外也不愁一个多边形的每一个内角都相等，且一个内角与一个外角的度数之比为m：n，其中m，n是互质的正整数，这个多_百度知道
提问者采纳
设多边形的边数为a，多边形内角和为（a-2）180度，外角和为360度m：n=180（a-2）：360a=，因为m，n 是互质的正整数，a为整数，所以n=2，故答案为：，2．
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出门在外也不愁[高中数学]Cmn和nCr这两种表示方法,两种表示方法n是否一样?在表示方面,m=r,n=n 吗?m=n,还是n=r?是指组合公式._作业帮
[高中数学]Cmn和nCr这两种表示方法,两种表示方法n是否一样?在表示方面,m=r,n=n 吗?m=n,还是n=r?是指组合公式.
[高中数学]Cmn和nCr这两种表示方法,两种表示方法n是否一样?在表示方面,m=r,n=n 吗?m=n,还是n=r?是指组合公式.
是一样的，不过后者一般是二项式定理中专用的，前者就是表示普通的组合数萘的N溴代物和M溴代物种类相等问M+N=?这有什么 规律啊 |我 、就 不理解 了_作业帮
萘的N溴代物和M溴代物种类相等问M+N=?这有什么 规律啊 |我 、就 不理解 了
萘的N溴代物和M溴代物种类相等问M+N=?这有什么 规律啊 |我 、就 不理解 了
萘的1溴代物有 2 种萘的2溴代物有 6 种萘的3溴代物有 7 种萘的4溴代物有 12 种萘的5溴代物有 7 种萘的6溴代物有 6 种萘的7溴代物有 2 种萘的8溴代物有 1 种总共有8个可以取代的地方,你把1溴代物看成是7个H取代了其他的溴的物质,也是一样的...所以.M＋N＝8如图所示，两个完全相同的量筒里分别盛有质量相同的水和酒精，M、N两点到量筒底部的距离相等，则这两点液体的压强的大小关系是______．
∵M、N两点到量筒底的距离相等，∴根据m=ρV=ρSh可知，M、N两点以下m水＞m酒；又∵因为完全相同的量筒中，分别盛有质量相等的水和酒精，∴M、N两点上mM＜mN，即GM＜GN；∴根据P=
可知，PM＜PN．故答案为：PM＜PN．
阅读理解。
An exhausted (筋疲力尽的) looking woman came into the doctor"s office. She said, "Doctor, there
are dogs all over my neighborhood. They bark (犬吠) all day and all night, and I can"t get a good sleep."
"I have good news for you," the doctor said, taking out a small bottle. "Here are some new sleeping
pills (药片) that work like a dream. A few of these and your trouble will be over (结束)."
"Great, thank you." the woman was very glad to go back home with the pills.
A few weeks later, the woman came again, looked worse than ever (比以前更坏). She said, "Doctor,
your pills are not good at all. I"m more tired than before."
"I don"t understand how that could be," said the doctor, shaking his head, "Those are the strongest (最
强的) pills on the market."
"That may be true," answered the woman, "but I"m still up all night running after those dogs and when I
finally (最后) catch one, it"s hard to get him to eat the pills."1. The woman came to see the doctor because _____.
A. her dog was ill
B. she was bitten (被咬) by dogs
C. she couldn"t sleep well
D. her son was ill2. The doctor gave some pills to the woman for _____.
A. the dogs
B. herself
C. her son
D. her neighbors3. The woman got _____ in a few weeks.
B. healthy
D. well4. Which of the following is RIGHT?
A. The doctor gave the woman wrong pills.
B. The woman liked to run with the dogs.
C. The woman took the pills but the pills didn"t work at all.
D. The woman might feel better if she took the pills.5. When he heard what the woman said, the doctor might think that _____.
A. he gave the woman the right pills
B. the woman was a very clever person
C. the woman was very foolish
D. he should give the woman the pills again
阅读理解。
One day, a poor boy who was trying to pay his schooling by selling gods door to door found that he only had one dime (一角硬币) left. He was hungry so he decided to beg for a meal at the next house. However, he didn"t beg when a lovely young woman opened the door. Instead of a meal he asked for a drink of water. She thought he looked hungry so she brought him a large glass of hot milk. He drank it slowly, and then asked, "How much do I owe (欠) you?" "You don"t owe me anything," she replied. "Mother has taught me never to accept pay for a kindness." He said, "Then I thank you from the bottom of my heart." As Howard Kelly left that house, he not only felt stronger physically, but it also increased his confidence in God and the human race. He was about to give up before this point.
Years later the young woman became seriously ill. They finally sent her to the big city, where specialistscan be called in to study her rare disease. Dr. Howard Kelly, who was a famous doctor now was also invited for the consultation (会诊). When he heard the name of the town she came from, a strange lightfilled his eyes. At once, he went into her room. He recognized her. He went back to the consultation roomand decided to do his best to save her life. From that day on, he gave special attention to her illness.
Finally the woman was saved. Dr. Kelly asked the business office to pass the final bill to him. He lookedat it and then wrote something on the side. The bill was sent to her room. She was afraid to open it because she thought that it would take the rest of her life to pay it off. Finally she looked, and read these words, "Paid in full with a glass of milk. Dr. Howard Kelly" Tears of joy came into her eyes as she prayed (祈祷) silently: "Thank you, God. Your love has spread through human hearts and hands."
1. When Howard Kelly was a boy, he was very _____.
A. rich B. poor C. strong
2. The young woman gave Kelly _____.
A. a glass of milk B. a glass of water C. a meal
3. Why didn"t Howard Kelly give up at last? Because _____.
A. he loved the young woman B. he wanted to pay tie woman the money for the milk C. the woman"s kindness gave him the confidence in God and the human race
4. Which is right according to the text?
A. The woman paid the bill with a glass of milk. B. The woman was afraid to see the bill because it would take all her life to pay it off. C. Dr. Kelly paid the bill instead of the woman.
5. Which is the best title for the text?
A. Howard Kelly. B. A Glass of hot Milk.C. The Woman and Dr. Kelly.
I admire Mother Teresa because she ______ everything for _______.
A. the others
B. the otherC. others
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