A.1/3~1/2 B.1/4~1/3 C.1/5~1/4 D.1/6~1/5
A.1/3~1/2 B.1/2~2/3 C.1/3~2/3 D.2/3~3/4
A.減小 B.升高 C.不變 D.忽高忽低