有關句子tense 的問題

I have eaten a chicken wing = 我食左一隻雞翼

留意 :
1. 有時我們可以使用 present perfect tense 或者 past tense 去描述同一件發生在過去的事。所不同的是 past tense 可以提到確切發生的時間，但 present perfect tense 卻不可以。
2. Present perfect tense 有很多用途，不是每一次都是和 past tense 同意思。

早前我上載了一些錄像在Youtube，解釋一些基本的文法規則，這個錄像正正回答你的問題，希望可以幫到你。
http://www.youtube.com/watch?v=EvC5ID9iCCM

I have eaten a chicken wing => 我已經完全食哂一隻雞翼

I am just finish a chicken wing => 宜家我食完隻雞翼。

Iｈａｖｅ　ｅａｔｅｎ　ａ　ｃｈｉｃｋｅｎ　ｗｉｎg 我剛剛食左只雞翼

I have just finished earing a chicken wing 宜家我食剛完隻雞翼。

如果12:45-12:47 食隻雞亦

12:45-12:47 嘅時候講: I am eating a chicken wing.
12:47 嘅時候講: I have eaten a chicken wing.

12:47以後講: I ate a chicken wing (from 12:45 to 12:47.)

2013-12-13 19:58:12 補充：
12:47 嘅時候講: I have eaten a chicken wing.(宜家)我食完隻雞翼

上面果句係解「我已經食左隻雞翼。」

A chicken wing has already been eaten!
Chicken wings had always been liked by me.
Present perfect tense should be used.
When in doubt;Idiomatic language uses words in a way that sounds natural to native speakers of the language.
Hence:-I have eaten a chicken wing;=idiomatic English; in a way that sounds natural to native speakers of the language