e going to do 计划,安排,准备,打算做某事
be to do即将做某事或应当做某事
be due to do应当做某事
be about to do即将做某事(不能同将来时间连用)
如:I'm going to see my grandparents next Sunday .
The film is to start .
The film is due to start at 6:30 this afternoon .
She was about to leave the room when the telephone rang .
The film is about to start .