有英文tense 問題想問問

無需要想到咁複雜, 因為曾經有過既野, 就算跟住無左, 都唔會影響"曾經存在" 呢個事實.

不過你用到 just, 就要用 have / had, 所以第一句要改為 I have just visited......

其實轉左彎想一下, 如果你曾經有屋住, 而家間屋爛左, 咁唔通令你曾經住過呢個事實, 突然變得無家可歸??

Warning:-You must table an amendment;Do you mean "Pack something up again"?Your composition is very poor. Did you study English Grammar ?
Errors and Corrections:-(Subject:-by the time I left.)
When I was in ABC Dept Store at the highest level,
I have seen the entire Dept. Store.
------>There were many booths on each floor.
When I arrived at the lowest level(=basement) ready to leave,
I saw all the previous booths were gone, by the time I left, (as if by magic).
When I left the Dept. Store, I said:-
------->I have just visited ABC Dept Store
and there were many booths.

Have you seen the problem ?
The problem is "How come the previous booths by the time I left at the basement have gone? (as if by magic)

It is comparable to the problem:-
How come my previous house by the time I left, at Shek Kip Mei Resettlement, has gone? (as if by magic)

There were many booths at the ABC department but they were gone by the time I left.

I have just visited ABC Department Store and there were many booths.