两人素不相识。
The two are total strangers.
to be total strangers (idiom)
Every character draws itself, stroke by stroke. Then grab the brush: trace it yourself and hear the word when you finish.
Nice writing!
Chinese words snap together like bricks. Every word below shares a character with this one, so you are already halfway to knowing it.
两人素不相识。
The two are total strangers.
素不相识的人帮了他。
A stranger helped him.