单项选择题
A.辙叉心轨尖端至心轨宽40mmB.辙叉心轨尖端至心轨宽50mmC.辙叉心轨尖端至心轨宽30mmD.辙叉心轨尖端至心轨宽20mm
A.45~49B.43~49C.45~47D.42~49
A.40B.42C.44D.46