A.
B.
C.
D.
[单选题]A.B.C.D.
[单选题]A.必要条件B.充分条件C.充要条件D.以上都不对
[单选题]A.6B.7C.8D.9E.10
[单选题]A.12B.16C.21D.25E.30
[单选题]A.1~2次B.3~4次C.5~6次D.10次
[单选题]A.5.25c㎡B.4.65c㎡C.3.75c㎡D.4.45c㎡