危险废物填埋场场址距离地表水水域的距离最小距离为( )。
A．50m
B．100m
C．150m
D．500m
参考答案：C
任何植物种子都含______和______两类物质．
We _____ have proved great adventurers, but we have done the greatest march ever made in the past ten years.
A. needn't
B. may not
C. shouldn't
D. mustn't
