解析法求解平面汇交力系的平衡问题,需要对力求投影。
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如果一个力在某轴上的正交分力与坐标轴的指向相同,那么这个力在该轴的投影就为正。
A. 对
B. 错
After a while an agreement _____.
A. was arrived at
B. was arrived in
C. was arrived
D. has been arrived
I _____ that he would be able to leave tomorrow, but it's beginning to look diffcult.
A. hope
B. had hoped
C. hoped
D. am hoping
在课程中,遭受失恋应激的女孩子将红墨水看成:()
A. 惨烈的一汪血
B. 滴着血的嘴唇
C. 烂漫的山花
D. 在课程中未说明