pigs are usually in dirty water or mud .mud can ----insects

选择KEEP OFF
KEEP FROM是直接加上去DOING STH
KEEP OFF可以
比如
They lit a fire to keep wild animals off.
他们燃起篝火防止野兽接近.
PREVENT FROM,是PREVENT SB FROM DOING STH OR STH..
是避免的意思,可这里不该这么用.
请选择我,一定是对的,)