A.30°
B.45°
C.60°
D.90°
[单选题]A.B.C.D.
[单选题]A.2B.4C.6D.8
[单选题]A.6kTB.10kTC.6RTD.10RT
[单选题]A.1/4B.2/3C.3/16D.3/2