( ) 21.This is_____ eraser. It’s ____yellow eraser.
A. a; a B. an; a C. an; an
( ) 22. We have socks ______ all colors _______ a very good price.
A. in, on B. in, at C. on, at
( ) 23. ---Do you think the history class is ____? ---Yes, we all like it.
A. interesting B. difficult C. boring