My hobby is collecting stamps.为什么要用ing的形式啊?

swimming,hobby,my,is. My favorite hobby is my hobby is painting. my hobby is draw还是my hobby is drawing my hobby is drawing 还是my hobby is drawing pictures My hobby is dance还是My hobby is dancing? my hobby is [ ] [play] backetball My hobby is collecting stamps. Collecting stamps is my hobby. ----(play) basketball is my hobby. my hobby is ------- old coins . My hobby is reading books. my hobby is _____ football my favourite hobby is playing my hobby is (go)fishing _____(dance)is my hobby.____(sing) is his hobby.____(read) is our hobby. My hobby is Collecting Stamps 的作文 （）绘画is my favourite hobby