If you want to lend a hand and need the necessary information, you may go to ________.
A. your school
B. a social service committee
C. the library and churches
D. any places of the above
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In fact, you are able to do something for those who need help.
A. 对
B. 错
变形观测的正负号规定中,对水平位移向_______为正,向_______为正;反之为负。对竖向位移,向_______为正,向_______为负。
引张线观测设备主要由_______ 、_______、_______等三部分组成。