起钻时，钻头泥包易产生（）作用，从而导致（）。
参考答案：抽汲；松软地层垮塌
—How about going camping with us this weekend?
—_____
A．Is that right?
B．I’d like to, but I have no time.
C．What are you planning?
D．What’s for?
如何对热力试验员进行考核？
