问题 填空题

为捍卫祖国海疆,人民解放军某航空兵大队在南海上举行了多次实兵实战对抗演习.在演习过程中,一空中加油机给某歼﹣10战机进行空中加油,加油后该歼﹣10战机仍以原来的高度和速度匀速飞行,则该战机的动能   ,机械能   (选填“增大”、“减小”或“不变”).

答案

增大;增大

题目分析:动能大小的影响因素:质量和速度,质量越大,速度越大,动能越大;

重力势能大小的影响因素:质量和高度,质量越大,高度越高,重力势能越大;

根据影响重力势能和动能的因素分析能量变化,再根据机械能等于动能加势能来最终做出判断.

歼﹣10战机在空中加油后,其质量增大,速度不变,因此,其动能增大;同时其高度不变、质量增大,其重力势能增大.故其机械能也一定增大.

点评:解答此题首先要明确动能和势能的影响因素,再注意分析飞机在加油后,是哪一个量发生了变化,对动能、势能、机械能分别造成了怎样的影响

完形填空

第二节完形填空(共10小题;每小题1分,满分10分)

阅读下列短文,掌握其大意,然后从每题所给的四个选项(A、B、c和D)中选出最佳选项。

One winter Nasreddin had very  31  money.His crops  32  very bad that year,and he  33  live very cheaply.He gave his donkey less food,and when after two days the donkey  34  just the same,he  35   to himself,“The donkey was used to  36  a lot.Now he is quickly getting used to eating less; and soon he will get used to living  37  almost nothing.”

Each day Nasreddin gave the donkey a little  38   food, until it was hardly  eating anything.

Then one day,when the donkey was going to market with a load of wood on its back, it suddenly   39 . “How unlucky I am,”said Nasreddin,“Just when my donkey had got used to eating hardly anything,it came  40  the end of its days in this world.

31.A.few          B. little        C. lot          D. much

32.A.had been      B. has been    C. was being     D. is being

33.A.has to         B. have to     C. had to       D. must have to

34.A.1ooks         B. is seen     C.  looked       D. was seen

35.A.says          B. say        C. saying         D. said

36.A.eat          B. eating       C. have eaten     D. being eaten

37.A.on          B. by          C. up            D. to

38.A.more        B. less         C. few           D. small

39.A.dead        B. dying        C. died          D. was dying

4 0.A.on        B. up           C.  in          D.to

问答题