当作业人员不清楚吊装现场的危险情况时，应（）。
A、对人员进行吊装前安全教育
B、停止吊装
C、应分工明确、坚守岗位
D、遵守该机械的操作规程
参考答案：A
根据上句完成下句，使两句意思表达基本相同。
1. Yesterday afternoon it rained heavily, so I borrowed an umbrella from Ed.
Yesterday afternoon it rained heavily, so Ed _____ _____ an umbrella.
2. Allan went to play football with his friends at once after he finished his homework.
_____ _____ _____ he finished his homework, Allan went to. play football with his friends.
影响塑料件收缩率的因素可归纳为：原材料、模具结构、塑件结构、（）。
