法兰联接由哪几部分组成?分几大类?
参考答案:
(1)法兰、被联接件、垫片或垫圈、密封元件和螺栓、螺母;
(2)分类:整体法兰、活套法兰、平焊法兰。
Look! Those boys are ____ a bus.[ ]
A. waiting for
B. wait
C. wait for
D. waiting
哪些种情况不属于临时救助范围?