How much more expensive do you think a flat in a downtown area is than in a suburban area

问题补充：

How much more expensive do you think a flat in a downtown area is than in a suburban area?

A. one

B. the one

C. that

D. those

答案：

(答案→)A. one

B. the one

C. that

D. those

解析：句意：你认为一个商业中心的公寓要比郊区的公寓贵多少？这里需要代词代替a flat，可以用one泛指前面的可数名词单数，the one是特指可数名词单数，that是特指可数名词单数或不可数名词，those是特指可数名词复数，所以选A。