Z1-03-18 质点作直线运动，位置矢量的方向一定不变。
查看答案
Z1-03-22物体具有恒定的加速度，必作匀加速直线运动．
A. 对
B. 错
The author’s purpose in writing this passage is to explain .
A. why it is necessary for us to help others
B. how to help others
C. who most need help
D. what community service is
The main idea of Para. 2 is that .
A. many people need help, but nobody sees and gives it
B. the organizations must depend on voluntary help
C. special help should be given to those who cannot easily get help
D. it is necessary to form organizations to give help to those who need it
Which of the following statements is NOT true?
A. The work of community service takes volunteers little time.
B. It is natural for most people to help others.
C. Voluntary help is needed in many places.
D. Community service means a lot to those who need help.
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