Of all the subjects I like history best because it gives ususeful knowledge of things in

问题补充：

Of all the subjects,I like history best because it gives ususeful knowledge of things in the past.

A. the;a

B. /;a

C. a;the

D. a;/

答案：

A. the;a

(答案→)B. /;a

C. a;the

D. a;/

解析： history为学科名词，不用冠词；a useful knowledge of...一门有用的知识。