I fall ___ asleep.为什么要填fast 而不是quickly

I fall ___ asleep.为什么要填fast 而不是quickly 1.As a heavy sleeper,I fall﹎﹎asleep A.quick B.fast C.quickly 为什么是be fast asleep 而不是be fastly asleep? fast fall asleep/ fall fast asleep 哪个对? I'll be back ___ quickly fast quick soon be fast asleep与fall asleep的区别. I am excited fall asleep. I can't fall asleep. I was interested in the film but my sister ___ (fall) asleep 英语翻译为什么要填asleep,原因 I ran to the net bar ___ .用fast 还是quickly fall asleep