11.6 be to和be going to
?
　　 be to 表示客觀安排或受人指示而做某事。
　　 be going to 表示主觀的打算或計(jì)劃。
　I am to play football tomorrow afternoon.　　 (客觀安排)
　I'm going to play football tomorrow afternoon. (主觀安排)