Hash算法一个公开的、双向的、可逆的数学算法。
参考答案:错
There was a girl _____ on the playground. [ ]
A. play
B. to play
C. played
D. playing
There seemed no end to their troubles; nowhere _________ upon a path.
A.they could come
B.could come they
C.come they could
D.could they come