某校园工程结构裂缝事故梁侧面裂缝的主要原因是（）
A.水平剪切力
B.地基不均匀沉降
C.混凝土收缩
D.膨胀土效应
参考答案：C
--- What do you think of the plan ____ at the meeting?
--- Very good. But the most important is to put it into ______.
A．put up, action
B．put forward, practice
C．put aside, practice
D．put away, truth
氢气的浓度低于（）%，便不能点燃。
A、7
B、4
C、5
D、6
