Question

i think______(一定是）Jack that parked the car like that,for he is always doing so.

为什么标答是it must have been

Answer 1

it 是形式主语，代后面的从句，原来形式是it must be，用了完成时

追问

为什么要用完成时

追答

后面是parked

Answer 2

对过去事实的推测。。。

追问

那为什么是完成时 而不是it must be

追答

must （只用于肯定句）根据具体事实所做的很有把握的主观肯定判断和猜测：

　　“一定----，肯定---”：

　　--- You have worked hard all day, you must be tired. （对现在事实的判断）

　　--- It’s dark. Mother must be waiting for my return.

　　--- I didn’t hear the phone. I must have been asleep. （对过去事实的判断）

　　--- It must have rained last night, for the road is wet.
对过去事实的猜测用must have been

Answer 3

I think it must Jack that parked the car like that, for he is always doing so.

追问

标答是it must have been

Answer 4

MUST表肯定一定，而jack停车是过去并且已经完成，所以答案是it must have been

Answer 5

must have done表对过去的肯定猜测
注意should have done是本应该做了什么
详见高二情态动词语法