单项选择题
A.1张下铺 B.2张下铺 C.1张下1张中铺 D.3张下铺
A.5~6Cm B.5~7Cm C.5~8Cm D.6~9Cm
A.1/4~1/5 B.1/4~1/6 C.1/5~1/6 D.1/6~1/7