题目内容
I won't tell the student the answer to the math problem until he________on it for more than an hour.
[ ]
A.has been working
B.will have worked
C.will have been working
D.had worked
答案:A
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题目内容
I won't tell the student the answer to the math problem until he________on it for more than an hour.
A.has been working
B.will have worked
C.will have been working
D.had worked