--- _____ they taking a picture? --- Yes, they are. A. Am B. Is C. Are
当你的好朋友总是运气不佳时,你最应该对他说:______
The woman is old, but she looks_______.
It's very difficult, _______ I can do it myself.
Are you going toplay Ping-Pong _______ football?
The boy is sitting_______her father and mother.