是Have you decided ( ）on winter vacation?空格里为什么不能填what to do

是Have you decided ( ）on winter vacation?空格里为什么不能填what to do Have decided（ ） on winter vacation?这个句子括号中为什么不能用what to do? Have you decided what to do next?中what为什么不能换成how? have　you　decided　what　to　do　on　the　　weekends?（写同义句 Have you decided what you want to do after school did you do (anything)fun on your vacation 括号里为什么要填anything急 what will you plan to do on the coming vacation What are you going to do on the winter -What do you do on vacation? i'll tell you ___ ___ ____ I have decided what to do.这道题该填什么 the winter vacation is coming ,what are you going to do?的意思, The winter vacation is coming what are you going to do?