A.2
B.3
C.4
D.5
[单选题]A.2B.3C.4D.5
[判断题]对错A.对B.错
[单选题]A.B.C.D.
[单选题]A.30°B.45°C.60°D.90°
[单选题]A.B.C.kTD.