1) shall用於第一人稱，常被will 所代替。
will 在陳述句中用於各人稱，在爭求意見時常用於第二人稱。
which paragraph shall i read first.
will you be at home at seven this evening?
2) be going to +不定式，表示將來。
a. 主語的意圖，即將做某事。
what are you going to do tomorrow?
b. 計畫，安排要發生的事。
the play is going to be produced next month。
c. 有跡象要發生的事
look at the dark clouds, there is going to be a storm.
3) be +不定式表將來，按計畫或正式安排將發生的事。
we are to discuss the report next saturday.
4) be about to +不定式，意為馬上做某事。
he is about to leave for beijing.
注意：be about to 不能與tomorrow, next week 等表示明確將來時的時間狀語連用。