I am not familiar ______ this machine.A.to B.toward C.with D.about

选C
be familiar with 的主语是人
be familiar to 的宾语是人,主语通常是物
例如:
I am familiar with the way home.

The book is very familiar to me.

C be familiar with是词组

A
be familiar to是对什么熟悉的意思

C be familiar with是词组 "与......相同"的意思