【题目】Mary _________ really hard on his book and thinks he'll have finished it by Friday.
A.worked
B.hasbeenworking
C.hadworked
D.hasworked

【答案】B
【解析】句意：Maty 一直努力写书，我想他到周五为止将已经完成了。用现在完成进行时表示从过去到现在一直进行的动作。所以选B。