题目

如图，直线l∥m，等边△ABC的顶点B在直线m上，∠1=20°，则∠2的度数为( )A. 60° B. 45° C. 40° D. 30° 答案：【答案】C【解析】如图，延长AC交直线b于D，∵△ABC是等边三角形，∴∠3=60°−∠1=60°−20°=40°，∵a//b，∴∠2=∠3=40°.故选：C.Now there is a danger ________ the ground may fall in under the heavy traffic.A．whether B．if C．X D．that