对封闭不良的钻孔，距钻孔（）m时应采取超前探水或其它防范措施。
A.50
B.30
C.10
D.20
参考答案：D
Tom and Li Lei _______ fruit very much. [ ]
A. likes
B. eats
C. like
D. has
我们应该把马列主义的理论来武装自己。
