幾時用past perfect tense ?

動詞的過去完成時態的形態是：had + 動詞的過去分詞
動詞的過去完成時態表示：

過去某一時間之前已經完成的動作或狀態
使用這種時態，多會涉及兩個動作或狀態。一個在前，一個在後。
敘述前面的動作或狀態，動詞要用過去完成時態；敘述後面的動作
或狀態，動詞要用一般過去時態。

例如：

I had taken my supper when he arrived.
﹝當他到達時，我已吃完我的晚餐。﹞
※ 上述句子涉及兩個動作，一是「他到達」，二是「我吃晚餐」。
「我吃晚餐」在前，要用過去完成時態；「他到達」在後，要用
一般過去時態。

※ "I had taken my supper" 是主句， "when he arrived" 是從句
﹝副詞從句﹞。

※ 圖示：

過去 現在 將來
_________________________│__________________________
│ │
past perfect simple past
Had you finished your work when I visited you yesterday?
When I reached the station, the train had already started.
He said that his father had returned to America.
After I had done my work, I played tennis.
※ 若用了 "After" 這個詞，可不用過去完成時態，因已有「之後」
的含意。即：

After I did my work, I played tennis.
在這種情況下，"After I did my work"是：
" Simple past Tense in form, but past perfect Tense in meaning."
﹝形式上是一般過去時態，但意義上是過去完成時態﹞
同樣，I had seen your father before I went.亦可寫成：

I saw your father before I went.
用英文表示「我看電視之前已完成功課」，可以有多種方式：

1. When I had finished my homework, I watched television.
2. I had finished my homework when I watched television.
3. I had finished my homework before I watched television.
4. I finished my homework before I watched television.
5. After I had finished my homework, I watched television.
6. After I finished my homework, I watched television.
7. I finished my homework and I watched television.
﹝時間順序法﹞
※ 「時間順序法」：按事件的先後次序連接起來。
如果涉及三件或以上的事件，就更需要用這種方法了。例如：

I reached the station, the bell rang and the train started.

過去 現在 將來
_________________________│__________________________
│ │
past perfect simple past
Had you finished your work when I visited you yesterday?
When I reached the station, the train had already started.
He said that his father had returned to America.
After I had done my work, I played tennis.
※ 若用了 "After" 這個詞，可不用過去完成時態，因已有「之後」
的含意。即：

After I did my work, I played tennis.
在這種情況下，"After I did my work"是：
" Simple past Tense in form, but past perfect Tense in meaning."
﹝形式上是一般過去時態，但意義上是過去完成時態﹞
同樣，I had seen your father before I went.亦可寫成：

I saw your father before I went.
用英文表示「我看電視之前已完成功課」，可以有多種方式：

1. When I had finished my homework, I watched television.
2. I had finished my homework when I watched television.
3. I had finished my homework before I watched television.
4. I finished my homework before I watched television.
5. After I had finished my homework, I watched television.
6. After I finished my homework, I watched television.
7. I finished my homework and I watched television.
﹝時間順序法﹞
※ 「時間順序法」：按事件的先後次序連接起來。
如果涉及三件或以上的事件，就更需要用這種方法了。例如：

I reached the station, the bell rang and the train started.

Past Perfect
我在加入(joined)本公司之前曾受過一些有關培訓
- I had had some related training before I joined this company.
(the time when I joined the company is treated as the benchmark, something happened sometime before I did something)

Present Perfect (already, since..)
- I have finished my homework already.
(the action/task/event is completed/happened at some unspecified time before NOW, the benchmark)

Past Perfect Continuous
- I had been eating all day long before the buffet even began.
那自助餐還沒開始(began)我便經已整天沒停的在吃
(similar to present perfect continuous but treat the benchmark as the moment when the buffet began, since some unknown time before the buffet began, which is in the past, that action has been going on)

We use Past Perfect Simple Tense under these situations:

-action taking place before a certain time in the past
-sometimes interchangeable with past perfect progressive
-putting emphasis only on the fact (not the duration)

e.g. He had won five matches until that day. (action taking place before a certain moment in time; emphasises the result)

We use Past Perfect Continuous Tense under these situations:

-action taking place before a certain time in the past
-sometimes interchangeable with past perfect simple
-putting emphasis on the duration or course of an action

e.g. He had been playing football for ten years. (action taking place before a certain moment in time (and beyond), emphasises the duration)