I recognized him by his walk.

我根据他走路的样子认出了他。

《牛津词典》

I recognized him as soon as he came in the room.

他一进屋我就认出了他。

《牛津词典》

I recognized him as soon as I saw his back.

我一看到后身，就认出是他。

《新英汉大辞典》

"We might have crossed paths, but I wouldn't have recognized him, " said Ben Leung, a 27-year-old pharmacy student who lives on the first floor.

WSJ: Shooting Suspect Built Arsenal by Mail Order, Police Say

But I keep pushing him and hoping he'll be recognized for the brilliant artist he is.

NPR: The Best Living Songwriters