look like you've seen a ghost

to look very shocked

(某人)看上去非常震惊

What's the matter? You look like you've seen a ghost!

到底怎么啦，瞧你一副见鬼了的样子!

Suddenly, Jamie looked like he'd seen a ghost. He went pale, and I thought he was going to faint.

突然间，杰米就像见了鬼一样。他脸色苍白，我以为他要晕倒了。