Zoos are terrible places for animals to live.这句话怎么理解呢?

题目

Zoos are terrible places for animals to live.这句话怎么理解呢?
人教版九年级英语P120的3A的课文里面,有这样一句话——
Zoos are terrible places for animals to live.
这句话中,为什么live后不加in呢?
课文接下来又出现了句子：I have never seen one I liked or one that was suitable for animals to live in.
为什么这里又加了live后面in呢?
语法上应该怎样理解这两句话?
谢谢!

答案

答案已经修改得更加易懂了,有哪里不懂请提出…我会帮你解释的,打字真的很累…
这两个例句都是正确的.
诚然,当动词不定式作定语时,to do与所修饰的名词是介词+宾语的关系,（比如这里是live in the zoo）就应当加上适当的介词,使得结构完整.如：Here is a seat for you to sit on.Please give me a pen to write the telephone number with.所以,第二个例句用了介词.
但是,当名词为time、place、way时,可以/应当省略相应的介词（如你句子中的in）,显得更地道.（这句话是复旦大学语法指南上的原话）如：He had no place to live and thus died in the street.
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衷心地祝你快乐!…