Question

新概念英语第125课语法问题

Can't you come in and have tea now,Peter?
Not yet.
I must water the garden first.
Do you have to water it now?
I'm afraid I must.
Look at it.
It's terribly dry.
What a nuisance.
Last summer it was very dry too.
Don't you remember?
I had to water it every day.
Well,I'll have tea by myself.
That was quickly!（这里为什么要用WAS从语法上看貌似不需要用过去式表达吧）
Have you finished already?
Yes.You look out of the window.
It's raining.
That means you don't need to water the garden?need to 也算情态动词嘛？后面跟的动词也必须是原形吗？
That was a pleasant surprise.这里也是同样的问题。感觉这句话就是在当下时间说的当下的事啊
It means I can have tea now instead.

Answer 1

That was quickly!  that 指代前文中浇花这件事，发生在过去，所以。。。

need有2种用法 1是做情态动词 后接原形 其他情态动词都是后接原形，2是作动词，后接不定式

构成need to 结构

倒数第二句话，that指代前文中的下雨这件事，发生在过去，所以...

童鞋，我向你推荐魔方格作业神器，很好用的哦

Answer 2

这是祈使句。有now不一定非得用现在进行时。这里是情态动词can+动词原形的句子。

追问

祈使句是祈使句，但根据句子的上下文没感觉出来要用过去时态啊。
need to 算情态动词？