单项选择题
A.1 B.2 C.3 D.4
A.3 B.4 C.5 D.6
A.5 B.10 C.15 D.20
A.3~5 B.2~4 C.4~6 D.1~3
A.4~6 B.3~5 C.1~3 D.2~4
A.90% B.80% C.70% D.60%
A.4 B.3 C.2 D.1