she found him --------a very smart boy .

问题描述:

she found him --------a very smart boy .
be 错了吗

没错
find( think, suppose, declare, consider, prove .) 等词用不定式做宾补时一般为 to be 不定式
如:
I think him to be an honest boy.
He proved himself to be an outstanding scientist.
I found the boy to be very clever.
.