21. –-Now that you like the house so much, why not buy it?
---Well, I can’t afford _______house.
 A. that a big     B. a big that     C. a that big     D. that big a
22. ________the city centre, we saw a stone statue of about 10 metres in height.
 A. Approaching     B. Approached   C. To approach   D. To be approached