The cost of oil is less than of gas.A. itB. oneC. the oneD. that

问题补充：

The cost of oil is less than of gas.

A. it

B. one

C. the one

D. that

答案：

A. it

B. one

C. the one

(答案→)D. that

解析：在比较级中用代替前面的不可数名词。