We always keep spare paper, in case we run out.
A. too much
B. a number of
C. plenty of
D. a good many
网友回答
A. too much
B. a number of
(答案→)C. plenty of
D. a good many
解析：句意：我们总是准备着大量多余的纸张，怕万一我们用完没有了。A. too much太多； B. a number of 许多，修饰可数名词。C. plenty of许多，修饰不可数名词。D. a good many许多，修饰可数名词的复数。
根据句意故选C。