问一个有关英语语法的问题

The kettle water ______(boil) for 3 minites before it _____(take) away for the stove.

请问这两个空该怎么填?
知道的朋友帮忙回答, 并讲讲道理, 谢谢了

该题有三种答案:
1、The kettle water has to be boiled for 3 minutes before it can be taken away for the stove.
(这壶水需要在炉子上煮3分钟才可以拿下来。)
2、The kettle water had to be boiled for 3 minutes before it colud be taken away for the stove.
(这壶水需要在炉子上煮3分钟才可以拿下来。)
3、The kettle water had been boiling for 3 minutes before it was taken away for the stove.
(这壶水在炉子上沸了3分钟才被拿下来。)

1和2是描述一个条件,讲“水”什么时候可以从火上取下来。
3讲的是一个事实,讲“水”是什么时候被取下来的。

前两个句子中,boil是及物动词,与to have to (必需)共同构成被动态。
第三个句子里boil是不及物动词。由于讲述的都是发生过的事情,因此需要使用过去式和过去完成式。
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第1个回答  2008-10-07
前边是had been boiling,后边是was taken
首先就句型及意思而言就决定了前边是过去完成时,后边是过去时,而且是被动语态
由于水持续沸了3分钟,也就是一直在沸,所以要在过去完成时的基础上加上进行时
当然也可以是has been boiling和is taken,不过要看具体语境
第2个回答  2008-10-07
had been boiling ,was taken
壶里的水滚了三分钟之后才被从炉子上拿开本回答被提问者采纳
第3个回答  2008-10-07
has to be boiled; is taken
整句时态应为一般现在时
第4个回答  2008-10-07
The kettle water was boil for 3 minutes before it had taken away from the stove.