A.0
B.
C.
D.
[单选题]A.0B.C.D.
[问答题]
[判断题]对错A.对B.错
[单选题]A.π/6B.π/4C.π/3D.π/2
[单选题]A.2天B.4天C.7天D.14天E.30天