单项选择题
A.≤0.05B.≤0.1C.≤0.15D.≤0.2
A.0.2-1.5B.0.5-2.0C.0.2-0.5D.1.5-2.0
A.30°一60°B.60°一90°C.30°一90°D.90°一120°