20．-Poor Steve! I could hardly recognize him just now!

　 -________．He has changed so much．

　　　 A．Never mind　　　 B．No problem　　　 C．Not at all 　　　　 D．Me neither

19．I just don’t understand _______ that leads to so many teenagers becoming addicted to playing computer games．

　　　 A．why it does　 　 B．what it does　 C．what it is　　 　 D．why it is

18．Amy joined a painting group but didn’t seem to _______, so she left．

　 　　 A．show off　 　　　　 B．go up　 　　　　　 C．fit in　 　　　　　　 D．come over

17．--- Did you enjoy yourself last night?

--- Yes, it’s very nice of you．I appreciated ________ to the party．

　　　 A．to be invited　　　 　　　　　　　　　　　 B．to have invited　

　　　 C．having been invited　　 　　　　　　　 D．having invited