be going to 句型的用法
1. 意义：be going to是"一般将来时"的一种表现形式，表示将
来某个时间将要发生的动作或存在的状态，意思为"打算，将要"。

其中"be"会根据主语的人称变化成"is,am,are"等形式。

"to"跟在它后面的动词必须是动词原形。

通常和tomorrow, this
evening(week/ year…), next week(Sunday…)等连用
2. 结构：主语+be(am/is/are)+going to+动词原形
（系动词（am/is/are）的用法：我（I）用am,你（you）用are, is 连着他（he）她(she)它(it),凡是复数都用are）
3.肯定句：主语+be(am/is/are)+going to +动词原形
A.He is going to buy a book after school.
B. I am going to climb mountains.
4.否定句：在系动词（am/is/are）后+not
A. He isn’t going to buy a book after school.
5.一般疑问句：Be+主语+going to +动词原形（把系动词提到主语前面）
A.Is he going to buy a book after school? -----No, he isn’t.
B.Are you going to climb mountains? ------Yes, I am.(变一般疑问句时，第一人称变为第二人称)
6.特殊疑问句：疑问词+be +主语+going to +动词原形
He is going to have a picnic next Sunday. 下个星期天他打算去野餐。

---What is he going to do next Sunday?
----When is he going to have a picnic?。