The invention of paper was a great contribution tohuman civilization.A. a;aB. the;theC. /;

问题补充：

The invention of paper was a great contribution tohuman civilization.

A. a;a

B. the;the

C. /;/

D. the;/

答案：

A. a;a

B. the;the

(答案→)C. /;/

D. the;/

解析：paper 物质名词，意为“纸”，前面不加冠词；human civilization “人类文明”，习惯上前面也不用冠词。