用所给动词的正确形式完成短文。

I can't remember when I started collecting litter．It was when l got tired of ___1___（see）litter nearby that I realized no one else was going to pick it up．

I live near a big square in Neijiang，Sichuan Province，I can ___2___（walk）there in three minutes! I used to love going there to play．But one day there was so much litter there that I ___3___（become）very unhappy．I decided I had to clean up the square．I wanted ___4___（feel）happy going there again．

I made my first visit to clean the square that afternoon．I ___5___（take）a big black rubbish bag with me．Ten minutes after starting to pick up litter，my bag was full! It had cans，bottles，broken glass and newspapers in it．From then on，I went to the square four times a month to pick up the litter．I often work there for three hours．It ___6___（make）me feel great to do something for the environment．

After each visit，I look at all the litter that I ___7___（find）．If any of it is recyclable（可回收的），I keep it．I can't understand why people drop litter．I ___8___（keep）picking it until they stop ___9___（drop）it．I know now I ___10___（do）a small bit to make our city cleaner，but I still think it is important．