I must be going 为什么be后要接go的ing形式啊?

I am afraid I must be going I must be going 为什么be后要接go的ing形式啊? I must be going 为什么be后要接go的ing形式啊? I'm afraid I must be going .这句话为什么用被动语态? I am afraid I must be going与I am afraid I must go的区别 I afraid I'm must be going. be going 是什么时态 I must be going.是动名词,还是现在分词? I must go与I must be going 有什么区别? i think you must be a teacher是什么意思must be为什么不是must are?must I think i am going to()next Sunday A be free B free选哪个?为什么? 英语情景交际单选-the movie will begin in five minutes.i must be going now.-ok.[ ]enjoy urself.a.it's interestingb.go slowlyc.stay longerd.see u.为什么选d而不选b呢? --it's getting late.I'm afraid I must be going now.--OK.( )a.take it easy b.see you c.stay longer d.go slowly I really must be going now,because I have classes in the early morning.怎么回答 英语释义题he college is(named after)George WashingtonA.called the name B giving the name Ccalled D given the same name as .I must (be off )now.A,turn off B going C be going D leave off I must be off now.It' time I _____ to schoolA.go B.to be caught C.being caught D.to catch这个选什么?为什么,不好意思。A.go B.went C.will go D.am going.但确实是B went. i am going to be sick为什么要用be? It ___ be quite late now.We must be going home.A.can B.must C.would D.may Who i was going to be?是什么意思?为什么不说Who i am going to be