be doing 是进行时态,表示正在发生的动作。如果be是am /is are 就是现在时行时,如果be是was /were 就是过去进行时
be going to do 是一般将来时态,表示将要发生的动作
它们的一般疑问句都是直接把be提到句首;否定句都是直接在be后加not.
如
He is doing his homework .
他现在正在做作业。
It's eight o'clock in the morning . They are having breakfast .
现在是早上8点。他们正在吃早餐。
They were having lunch at this time yesterday.
他们昨天这个时候正在吃午餐。
Is he playing basketball now?
No, he is playing football.
他现在正在打篮球吗?
不,他在踢足球。
He is going to play basketball tomorrow.
他明天打算去打篮球。
Are they going to plant trees next week ?
他们下周打算去植树吗?