为什么 I'M GOING SWIMMING 不是 TO SWIM?

I'm going home和I'm going to school为什么going home 不加to? I'm going to back home和I'm going back home哪个对?为什么 I'm going to back home和I'm going back home哪个对?为什么 i'm,going,higher I'm going to I'm going to I'm going to 为什么 I'M GOING SWIMMING 不是 TO SWIM? （ ）Sorry,Frank.I'm busy today.I can't go swimmi（ ）Sorry,Frank.I'm busy today.I can't go swimming with you.__________A.No problem B.You're welcome C.That's all D.Never mind I'm going away for a long time.为什么这里going后面不用加to呢? i'm not going to her house on friday night going为什么用ing 形式啊 i'm going to school和i'm going to school 哪个表达是对的呀,为什么? 英语语法问题I'm going to go cry和I' m going to cry哪句英语对,为什么呢? I'm fraid I'M going to be sick 可以把SICK的BE 为什么 I'm going swimming还是I'm going swim I'm going to marry I‘m going () () () () this weekend I want to join the swimming club改为同义句I want to_______ _______the swimmi