they do it by truns like human beings

they do it by truns like human beings

我想问这句话怎么解释
还有一句
If one of them dies,the other one becomes very sad and quiet for the rest of its life and sometimes it dies,too.

We didn't do it ____ they do now. 这段英文怎么翻译people cann't do some themselves ,they wanna you cann't do it! They must have arrived by now,haven't they? Let us do it by ourselves,-----------? Don't worry about what people think;they don't do it very often.这句怎么翻译啊 They say you can’t judge a book by 谁知道《Do they know it's Christmas 》的歌词? They sang happily until it got dark.=They didn't ------------until it got dark. People are always neglecting something they can do in trying to do something they can't do. when do you need it by?什么意思？