With _____ help of my teacher, I have made great progress.
A:the
B:a
C:an
D:/
化简:﹣3(m2﹣2n)
如图有三只相同的玻璃杯,盛有等质量的酒精、纯水、盐水( ρ 盐水> ρ 纯水> ρ 酒精),则甲、乙、丙玻璃杯中分别是:( )