He likes music so much that I think it right to buy him MP3 as birthday present.
| A．the; an; a | B．不填；an; the | C．不填；an；a | D．the；a; a |
.
It's reported that in the past 50 years around 80 percent of Beijing's courtyard houses ___________.
| A．had wiped out | B．have wiped out |
| C．had been wiped out | D．have been wiped out |
.
If I ___________ you would drop in, I would have stayed home waiting for you.
| A．have known | B．knew | C．would know | D．had known |
.
—When will you be back, Peter?
—___________ a couple of days.
| A．On | B．In | C．For | D．By |
.
. All books ___________ to the library more than three days late will be subject to a fine.
| A．return | B．returning | C．to return | D．returned |
.
When he was only thirty years old, he had already experienced ___________ most people only experience when they are much older.
| A．what | B．which | C．who | D．when |