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问题 单项选择题

使用直接控制系统操舵时，要使舵叶准确到达所需要的角度，应注意掌握（）

①船的回转惯性；

②控制开关操作及时；

③海况；

④船速。

A.①③

B.①②

C.①④

D.①③④

答案

参考答案：B

阅读理解

首字母填空：先通读下面的短文，掌握其大意，然后根据短文内容和所给首字母，在空格内填入一个适当的词，使短文意思完整。(共10小题；每小题0.5分，满分5分)

Tennis is in its second life. Its first game b 小题1:  in France. The name of the game comes from the French w 小题2:  "tennez". The English men c 小题3:  the game "tennis" when they watched the Frenchmen play 800 years ago.

The Englishmen liked the French game. Tennis courts were b 小题4:  in every park, in every city, just like today. The two countries played against each other. At first they played for h 小题5:. Then they won money. Later people began cheating（欺骗）to get money. Three hundred years ago the game was forbidden（禁止）to s 小题6:  the cheating. The game also d__小题7:___. Americans found the old courts when they went to Europe 100 years ago. They learned w __小题8:__  they could do about the game. They liked the game as the Englishmen did before. After returning home, the Americans built tennis courts. Tennis began to become p小题9:  in all the United States. Now it is one of the most e 小题10:  games in the world again.
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计算题

(20分) 如图所示，两物块A、B并排静置于高h=0.80m的光滑水平桌面上，两物块的质量均为M=0.60kg。一颗质量m=0.10kg的子弹C以v0=100m/s的水平速度从左面射入A物块，子弹射穿A后接着射入B并留在B中，此时A、B都没有离开桌面。已知物块A的长度为0.27m，A离开桌面后，落地点到桌边的水平距离s=2.0m。设子弹在物块A、B 中穿行时受到的阻力保持不变，g取10m/s2。求：

（1）物块A和物块B离开桌面时速度的大小分别是多少；

（2）求子弹在物块B中穿行的距离；

（3）为了使子弹在物块B中穿行时物块B未离开桌面，求物块B到桌边的最小距离。
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