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问题 填空题

一个不透明的袋子中有2个红球．3个黄球和4个篮球，这些球除颜色外完全相同，从袋子中随机摸出一个球，它是红球的概率为         ．

答案

根据题意可得：不透明的袋子中有2个红球、3个黄球和4个蓝球，共9个，从袋子中随机摸出一个球，它是红 * * 的概率为

填空题

I live in the country and my father was a farmer.51. ______
He is now forty-five year old. Because of years of 52. ______
hard work, he looks old than his age. When I was53. ______
young, he is used to tell me the importance of study. 54. ______
Father knows little about English and other subjects, 55. ______
but he usually gives me some good advices on how56. ______
to learn my lessons good. He is not only kind to me 57. ______
but also very strict in me. With his help, I’ve made 58. ______
great progress. I’ll never to forget what he taught 59. ______
me. I think my father is best father in the world. 60. ______
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单项选择题

韶山4型电力机车缓冲器、从板及尾框组装后，中心偏差是（）。

A.≤6mm

B.≤5mm

C.≤4mm

D.≤3mm
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