一、单项选择
( )1. —Mike had ______ unusual experience last week. He said he saw ______ alien in his garden.
—Really？I can't believe it!
A. a; an B. a; a
C. an; an D. an; a
( )2. A book in rich colors is a good ______for babies of three months old.
A. chance B. change
C. choice D. decision
