They are some pens some books some cards.A. ofB. orC. andD. but

问题补充：

They are some pens,some books some cards.

A. of

B. or

C. and

D. but

答案：

A. of

B. or

(答案→)C. and

D. but

解析：本题的含义他们是一些钢笔，一些书和一些卡片，表示并列使用and，故本题选C。