En inglés, normalmente usan la expresión » I know first hand».
«I know it first hand» también es usado. Sin embargo, en lugar de decir «I know it first hand», normalmente suelen decir, «I know it well».
-I know first hand (first-hand)
Example:
-I know first hand what terrorism is.
-I know first hand the national product.
–I know it first hand
Example:
-English is very easy if you are determined. Believe me, I know it first hand (I know it well).
-Norman: There’s a nice restaurant called Flamingo.
Anabel: Ah yeah, I know it first hand (I know it well), as I’m there most weekends.