Question

【题目】We ______ on it for many hours, but we have not yet reached any conclusion. ( )

A.are being workedB.are workingC.have been workingD.have been worked

Answer 1

【答案】C

【解析】

句意：我们已经做了很多小时了，但我们还没有得出任何结论。根据but后时态，可以判断出到现在还没有得出结论，有可能还要继续下去，所以要现在完成进行时。故选C。