Are these evaporation lines?

my girlfrend has taken 3 tests this week and they have all come up with lines but very faint, the latest one came up a bit more visable but it is not as thick as the control window and all off these tests took up to two hours to appear are these evaporation lines ??? allso she is showing allot of signs one being allot of discharge through out the day is this a very big sighn ?? help!!!