呢句英文用咩 tense 架 ?

1. Present tense
I know who he/she is.

2. Present tense.
I know you. or
I know who you are.

3.Past tense, present perfect tense
I could hardly recognize him. He has lost a lot of weight.

樓上咁講過份簡化啦。我想問下，其實你係乜野情況之下要講呢幾句？
事實上三個都係敍述緊一ｄ發生左o既事，除係第三者用個鏡頭拍住你做緊乜，然後一路好似講波咁旁述！所以三句o既基本都係 past tense。不如我直情將呢三句寫出o黎啦：
1. As we looked at that photo, I remembered the name of the guy in it.
2. While I was walking down the street, someone called my name. The guy and I looked at each other. I wanted to say I remembered him.
3. "I met Tom in the street just now! I could barely remember him. He has become so thin!"
頭兩句都好簡單咁記述兩件往事，但第三句則有所不同，因為當中記述往事之餘，仲有一句「好瘦左好多」，而佢變瘦已成事實，發生左，即係往事一椿，但係效果又持續至今（你見到佢時都係咁瘦），所以應該用 present perfect tense。

1) present tense.

2) present tense.

3) past tense.