The girl looked at me with a _____expression. Maybe the problem was quite ____.

A．puzzled; puzzling

B．puzzling; puzzled

C．puzzled; puzzled

D．puzzling; puzzling

混合液体在一定压力下升高温度，使其气化，然后再降低温度，当其混合液体刚刚全部气化并保持在平衡状况下饱和气相冷凝时出现第一滴液体，这时的温度叫露点。