解析法求解平面汇交力系的平衡问题，需要对力求投影。
查看答案
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
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