be going to和will可以互换吗?

1.be going to 表示近期、眼下就要发生的事情,will 表示的将来时间则较远一些,如：
He is going to write a letter tonight.
He will write a book one day.
2.be going to 表示根据主观判断将来肯定发生的事情,will表示客观上将来势必发生的事情.
He is seriously ill.He is going to die.
He will be twenty years old.
3.be going to 含有“计划,准备”的意思,而 will 则没有这个意思,如：
She is going to lend us her book.
He will be here in half an hour.
4.在有条件从句的主句中,一般不用 be going to,而多用will,如：
If any beasts comes at you,I'll stay with you and help you.

be going to 比起 will 来说，多了一个“会去做”的层面。
I will go to school. 我要去学校。
I am going to school. 我会去学校。
I will be a teacher. 我要当老师。
I am going to be a teacher. 我会去一名老师。
体会出差别了吗？用be goin...