如图是某通道的侧面示意图,已知AB∥CD∥EF,AM∥BC∥DE,AB=CD=EF,∠AMF=90°,∠BAM=30°,AB=6m.
—I'm sorry I stepped outside for a smoke.I was very tired.
—There's no________for this while you are on duty.
化学课堂上老师演示了如图所示的几个实验: