凡在坠落高度基准面()以上,有可能坠落的高处进行的作业,均称为()。
参考答案:2米、高处作业
He has got himself into a dangerous situation ______ he is likely to lose control over the plan.[ ]
A. when
B. which
C. where
D. why
机电工程网络电子图书检索包括哪几方面的内容?