A.5 B.10 C.15 D.20
A.2 B.5 C.15 D.20
A.2/5~4/5(包括2/5及4/5) B.2/5~4/5(不包括2/5及4/5) C.1/5~4/5(包括1/5及4/5) D.1/5~4/5(不包括1/5及4/5)