问题补充：
Students in the USA spendtime their homework than we do.
A. little , to do
B. little, doing
C. less , doing
D. less , do
答案：
A. little , to do
B. little, doing
(答案→)C. less , doing
D. less , do
解析：根据后文有than，可知本题使用比较级，所以第一空应该为比较级，而spend 后接doing sth，故选答案为C
