1;the train leaves at 7:00
2;I'm going to leave.
3;有迹象要发生的事 Look at the dark clouds,there is going to be a storm.
4;We are going to die without air or water.
5;I am going to take part in a party at 19:00
6;be going to +不定式,表示将来.
a.主语的意图,即将做某事.What are you going to do tomorrow?