这里为什么主动表被动?I'mreallythirsty.Doyouthinkthiswaterissafe?Askthefarmeroverthere.AtodrinkBtobedrunk这里动词不定式是主动表被动,这里是什么形式.怎么能判断出是主动表被动,在同样类似

Question

这里为什么主动表被动?
I'm really thirsty.Do you think this water is safe ____?
Ask the farmer over there.
A to drink
B to be drunk
这里动词不定式是主动表被动,这里是什么形式.
怎么能判断出是主动表被动,在同样类似的句子中?
难道 be+adj + to do 结构都是主动表被动?

Answer 1

你想一想,这里的safe后面加的应该是什么?
应该是：I'm really thirsty.Do you think this water is safe for you..
这里应该加的是for you.
所以隐含了动词真正的施动者“you”.
因此这里是用to drink
这里是It（This,That）＋be＋a／an＋adj.＋ n.＋to do的形式
在这种句型中,不定式与前面的名词若有动宾关系,动词不定式可改为动词不定式复合结构.例如:This is a difficult question to answer.这是个难答的问题.
question与to answer为动宾关系.to answer可改为 for me to answer.再如:
It is an easy sentence to translate.这个句子很容易翻译.
其实有很多不定式主动形式表被动的情况.要注意总结.
我想了下：大致有这几种：
一、在某些固定句型中,动词不定式作定语,用主动形式表被动意义.
1）have（give,show）sth.to do
2）It（This,That）＋be＋a／an＋adj.＋ n.＋to do
3）There ＋be ＋n.＋to do
二、在某些“形容词＋不定式”的结构中,不定式有被动意义,与句子主语构成动宾关系.其句型有:
1）n.＋be＋adj.＋to do
2）n.＋be＋too＋adj.＋to do
3）n.＋be ＋adj.＋enough to do
三、某些动词,如to let,to blame （责备）,to seek（寻找）用主动式表被动意义.
练习:选择填空.
1.The chair looks rather hard,but in fact it is very comfortable to __________.
a.sit b.sit on c.be sat d.be sat on
2.I'm hungry.Get me something __________.
a.eat b.to eat c.to be eat d.for eating
3.It is difficult for a foreigner __________ Chinese.
a.write b.to write c.to be written d.written
4.I have no more letters __________,thank you.
a.to type b.typing
c.to be typed d.typed
5.The car is rather difficult __________.
a.to repair b.to be repaired
c.repairing d.being repaired
6.He was nowhere __________.
a.to see b.to be seen c.seeing d.seen
7.She had no money __________ a birthday present for their children.
a.to buy b.to be bought c.bought d.buying
8.We waited for the work __________.
a.done b.being done c.to do d.to be done
答案:
1—5 bbbca 6—8 bad