杭州交通信息网钢珠多少可以带上火车:2006英语高考选择题
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32. I won't tell the students 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
为什么选a？不选b？
A. has been working
B. will have worked
C. will have been working
D. had worked
为什么选a？不选b？
has been working
一方面表示了过去的一小时中在做这道题，目前乃至以后还将接着做
另一方面 until句型后面虽然翻译成将来时态，但不能用will
b,c 出现了will
d had worked 表示在1小时内已经完成了那道数学题
不符合题意
至少要等学生们努力思考这道题1小时后，我才会告诉他们答案
是选A
对将来的虚拟
但是因为if/until等引导的条件状语从句不能用将来时态，所以用现在时态即可