present perfect tense和past perfect tense有咩difference嘅用法和意思?

行ｄ講句，分別就係一個係現在，一個係過去
圖片參考：http://hk.yimg.com/i/icon/16/10.gif
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其實 present perfect 都係講過去左o既事，但係：
１．present perfect 唔會講明發生時間，通常只係simple past會講（如 I saw him an hour ago. vs I have seen him just now.）
２．present perfect 用於講剛發生o既事 （如 I have talked to him on the phone.）
３．present perfect 講o既事發生左之後，同現在仍有密切關係，效果持續，如：I've broken my leg. 意思可以係 I broke my leg last week. 但依家呢？斷腳一日未好返，都仲可以用 I've broken my leg.
past perfect tense 都係以前o既事，但通常只係有兩件一先一後發生o既事，而你想交代兩件事o既時序關係時用。
10pm - I saw your question.
9:30pm - I had my dinner.
==> When I saw your question, I HAD HAD my dinner.
　　　　　　　　　　　　　　(v)↑ + ↑(past participle)