英文grammar問題

1) past prefect tense 當然有passive voice
past perfect 既passive 係 had + been + 過去分詞
例: She had been killed before the police arrived.
警察來之前, 她已被殺
had been killed 就係passive


主動寫法為: He had killed her before the police arrived.
主動式不加 been, 只有被動才加 been


2) When 都可以用present perfect 或 past perfect
present perfect: When we arrived, she has caught 10 fish
這裡的 when 與 since 相同: 當我們到達時, 她已捉了0條魚

past perfect: When we arrived, she had left already.
我們到達前, 她已走了.這裡的 when, 與before 相同

其實只要句子有before./after, 可以不一定用past perfect tense, 因為先後次序已清楚

After I (had) finished homework, I went to bed. (有冇had都明係先做完功課, 後上床)

Before we arrived, the bus (had) left. (有冇had 都明係我們到達前, 巴士已走了)

但如果用when去表達先後次序, 一定要用had
When we arrived, the bus had left.

如果唔用had, 意思唔同:
when we arrived, the bus left. (=我們一到, 巴士就走)

1)passive voice 有冇past perfect tense ??有既話要點用，冇既話點解？？

有呀, 例如:

Few days ago, the lost cars had been found by the cops.

那些失車前幾天才被警察找回.

2)"when"係未冇past perfect/present perfect/present tense 架？我想知點解？

When已經係個時式黎(當時, 幾時). 所以冇PERFECT式. 因為PERFECT式係有時間關係. 已用WHEN既句子入面唔可能有雙重時式喇. 一個WHEN已經代表了所有時間. 係英文黎講: 問人地: 你幾時返黎呀? 唔會問: 你岩岩幾時返黎呀?

所以都係話:

When did you leave the house?

passive voice of past perfect tense :

原本had + past participle
轉做 had + been + past participle

e.g. The tourists told the police that they had been robbed by 3 men.