-- Who broke the glass?
- I suppose _____ must be one of the children.
| A．the one | B．he | C．it | D．who |
.
Clearly, in a system ______________ every decision is made on the basis of tradition alone, it may be difficult to achieve progress.
| A．that | B．when | C．where | D．which |
.
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 |