A:果蝇的白眼
B:人的血友病
C:人的白化病
D:人的外耳道多毛征
马铃薯放入浓糖水中会浮起来。( )
已知:a、b、c是△ABC的三边长,化简 a+b+c2-b+c-a2+c-b-a2.
Ben goes to work ________ and his sister goes to work ________.