21. —We usually go hiking for vacation. I like it, but I want to try something more challenging this year.
—_____
A. Let’s go. B. Cheer up! C. Like what? D. Take care.
22. To test eggs , ___them in a bowl of water: if they float they are bad; if they sink they are good.
A. put B. putting C. to put D. to be putting
