“open fire”是不是英語有的？

If you "open fire" on someone, you start shooting at them.
If you "return fire" or you "return someone's fire," you shoot back at someone who has shot at you.
see p.586 Collins Cobuild English Dictionary for Advanced Learners (third edition)

這些是英文的「動詞片語」。

open fire=>火力全開；開槍.

yup
It means a fire that you light outside
for example to cook on, or a fire in a space in a wall of a building, with a chimney to take the smoke away
Chinese definition: 明火

Openfire ~意指 :開火
是英語的