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：考查数量的短语用法。Too much 修饰不可数名词；a number of 修饰可数名词；plenty of 修饰可数于不可数名词；a good many 修饰可数名词。句意为：我们总是存有大量的备用纸，以防用完了。