第一次世界大战期间,一位法国飞行员在飞行时用手抓住了一颗德国子弹,这个飞行员能很

题型:选择题

问题:

第一次世界大战期间,一位法国飞行员在飞行时用手抓住了一颗德国子弹,这个飞行员能很容易地抓住子弹的原因是(  )

A.飞行员飞行的速度不大

B.子弹飞行的速度不大

C.子弹相对于飞行员的速度不大

D.以上都有可能

考点:运动和静止的相对性
题型:选择题

位于澳大利亚西部沙漠中的波浪岩(下图左),是一块巨大而完整的花岗岩体,大约在25亿年前形成。经过日积月累的风雨冲刷和早晚剧烈的温差变化,渐渐地被侵蚀成波浪的形状。据此完成下列各题。

小题1:上面右为岩石圈物质循环示意图,上述波浪岩与图中数字表示的岩石类型一致的是

A.①

B.②

C.③

D.④小题2:波浪岩的形成过程依次是

A.固结成岩一风化剥蚀一侵蚀搬运一地壳抬升

B.岩浆侵入一地壳抬升一风化剥蚀一侵蚀搬运

C.地壳抬升一侵蚀搬运一岩浆侵入一风化剥蚀

D.侵蚀搬运一岩浆侵入一地壳抬升一固结成岩

题型:选择题

使用条件是暗室和紫外线,主要用于紫外光下观察DNA条带的仪器是()

A.蛋白测序仪

B.DNA测序仪

C.DNA扩增仪

D.分光光度计

E.紫外透射仪

题型:选择题

21世纪( )是我国发展的重要战略机遇期;“十一五”时期尤为关键。

A.头二十五年

B.头二十年

C.头十年

D.后十年

题型:选择题

快速型漏电保护装置动作时间与动作电流的乘积不应超过()mA·S。

A、20

B、30

C、40

D、50

题型:选择题

Almost everyone likes dogs, and almost everyone likes to read stories about dogs.
I have a friend. He has a big police dog named Jack. Police dogs are very clever. Every Sunday afternoon my friend takes the dog for a long walk in the park. Jack likes these long walks very much.
One Sunday afternoon, a young man came to visit my friend. He stayed a long time. He talked and talked. Soon it was time for my friend to take Jack out for a walk. But the visitor still stayed. Jack became very worried. He walked around the room several times and then sat down in front of the visitor and looked at him. But the visitor paid no attention. He went on talking. At last Jack got angry. He went out of the room and came back a few minutes later. He sat down again in front of the visitor, but this time he took the visitor’s cap in his mouth.

Jack sat down in front of the visitor because he wanted ______.

A. to see the visitor
B. to show the visitor how clever he is
C. the visitor to leave

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