be going to be,是 将要成为.
be going to have,是 将要有...
I am going to be a teacher.我将要成为一个老师.
I am going to have an English class.我将要有一堂英语课.
will have 和shall have 都有“将要”的意思,只不过后者更婉转一些,主要用于建议和提议.
We will have to hurry.
我们得快点.
They shall have practised more.
他们本该多多练习.