查人人中国名人网工业以太网连接器:2006英语高考一道选择题
来源：百度文库 编辑：查人人中国名人网 时间：2024/04/30 01:24:03
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?
这个叫做主将从现，not…until…句型要用主将从现，主句一般将来时，从句一般现在时（但意思表示将来时）。
has been doing是现在完成进行时 也就是正在进行中
will have worked表示过去的将来与句中until（用进行时态）不符
这是个not until 句式，后面要用一般现在时。。