单项选择题
A.10~12倍 B.3~4倍 C.1~2倍 D.6~8倍 E.20~30倍
A.7.35~7.45 B.7.10~7.20 C.7.30~7.40 D.7.45~7.55 E.6.90~7.15
A.1:1 B.1:1.5 C.1.5:1 D.1:3 E.2.5:1