葫芦式起重机当主梁下翼缘宽度磨损量达原宽度的10%，主梁应报废
参考答案：错
The most crucial time for project risk assessment is______．
A．when a problem surfaces
B．during the planning phase
C．during the close-out phase
D．after the project schedule has been published
在滑溜路面，应如何驾驶？（）
A.用低波行车，轻踏油门
B.用前进波，轻轻加油
C.紧握方向盘
D.用前进波，加油比平时要多
