Don’t ____sad(伤心难过的). Let’s go and fly a kite.

The water in the river nearby will be dirtier than before if nothing __________.

--- Have you ____ your key?--- No, I’ve ____ for it everywhere, but I can’t find it.

Lu Xu is known_________ a great writer and thinker.

 I have        from my hometown for about 6 years.