帮忙做一下，初中英语题。谢谢急

Question

请说明为什么谢谢
We ____(clean)the room before you came.
It's too late.I have to ____(go) immediately.
When we ____(arrive) the station, the train ___(leave).
Must I_____(finish) my homework first?
These are some photographs that I____(take)last month.
By the end of last week, I ____(read)three books.
The firl who we ____(see)just now is my classmate.
Bob ____(go)to school yesterday,because he was ill.

Answer 1

请说明为什么谢谢
We had cleaned(clean)the room before you came.[before you came(在你来之前)，表明动作在过去（came）以前，用过去完成时。]
It's too late.I have to go(go) immediately. [have to+动词原形，表示“不得不”]
When we arrived(arrive) the station, the train had left(leave). [arrived(到达)是过去的动作，而火车到达发生在“arrived”之前，用过去完成时：had left]
Must I finish (finish) my homework first?[情态动词must后面必须接动词原形]
These are some photographs that I took (take)last month. [时间是“last month(上个月)”，过去时间，用一般过去时。]
By the end of last week, I had read (read)three books.[“by the end of+过去时间 (到……末之前)”，表示“过去以前”，动词用过去完成时。]
The girl who we saw (see)just now is my classmate.[时间是“ just now(刚才)”过去时间，用一般过去时。]
Bob didn't go(go)to school yesterday,because he was ill.[时间是“ yesterday(昨天)”，用一般过去时。又根据意思理解，因为“生病”所以应该“没去上学”，用否定式。]

Answer 2

1.have cleaned现在完成时
2.go现在说的话一般现在时即可
3.arrived had left它是讲述过去发生的事第一个用一般过去时,
到站已经是过去车开走应是过去的过去过去完成时
4.finish情态动词后直接加动词原形
5.took前边是现在时后边是过去的时间一般过去时态
6.had read过去的过去 过去完成时态
7.saw一般过去时态
8.didn't go一般过去时态

Answer 3

cleaned 后面came说明了是过去式
go have to是情态动词后面接原形
arrived,was leaving 如果是过去发生的话。到达是点动词，而火车是正在离开
finish must情态动词+原形
took 后面说的是上个月
have read 截至。。所以是完成时
saw 说刚才
didn't go 因为病了，所以昨天没去上学

Answer 4

had cleaned
go
arrived at;had left
finish
took
had read
saw
didn't go

Answer 5

1.have cleaned 2.go 3.arrived,has left 4.finish 5.took 6.read 7.saw 8.didn't go