问题
不定项选择
如图所示，光滑半球的半径为R，有一质量为m的小球B用一细线挂靠在半球上，在小球缓慢上移过程中，细线对小球的拉力大小F和半球对小球的支持力N的变化情况是
A．两者都变小
B．两者都变大
C．F变小，N不变
D．F不变，N变小
答案
答案：C
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如图所示，光滑半球的半径为R，有一质量为m的小球B用一细线挂靠在半球上，在小球缓慢上移过程中，细线对小球的拉力大小F和半球对小球的支持力N的变化情况是
A．两者都变小
B．两者都变大
C．F变小，N不变
D．F不变，N变小
答案：C
My wife called,“will you come here and make your darling daughter eat her food ？I rushed to the scene. My only daughter,Sindu , 1 frightened. In front of her was a bowl filled with rice. She 2 disliked rice . “Sindu ,why don’t you take a few 3of this ？ Just for Dad ’sake . If don’t ,your mom will shout at me .”Sindu softened a bit and 4 her tears with the back of her hands.“OK,Dad.I will eat .But you should ……”Sindu hesitated.“Dad ,if I eat the rice ,will you give 5 I ask for ？”“Oh,sure .”She 6 eating the whole quantity . After the ordeal was through ,Sindu came to me ,“Dad ,I want to have my 7 shaved off this Sunday ！ “Darling ,we will be sad 8 you with a clean-shaved head .”“Dad ,you saw how difficult it was to eat the rice .”Sindu was in tears.“ 9 you promised to give me whatever I ask for.” It was 10 for me to call the shots .“Our promise must be 11 .” With her head clean-shaven ,Sindu had a round face .On Monday morning , I dropped her at her 12 .Just then , a boy shouted ,Sindu please wait for me ！13 struck me was the hairless head of that boy . “Sir , your daughter Sindu is great 14 .”a lady said to me ,“That boy who is walking along with your daughter is my son Harish .He is 15 from leukemia（白血病）. He lost all his hair due to the side 16 of the chemotherapy(化疗).He refused to 17 to school for fear of being laughed at . Sindu visited him last week , and promised him that she will take care of the teasing issue. But , I 18 imagined she would sacrifice her lovely hair for the sake of 19 ” . “My little angel , you are teaching me 20 selfless real love is ！” I wept.
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