题干
—Mummy, could you b
uy me a skirt like this?
—Certainly. We can buy __
______ one than this, but ________ this.
uy me a skirt like this? —Certainly. We can buy __
______ one than this, but ________ this.
A：a better; better tha
B：a good; as good a
C：a cheaper; as good a
D：a more expensive; not as good a
答案(点此获取答案解析）
C
行入射到三棱镜上，经棱镜折射后，交会在屏上同上点，若n1和n2分别表示三棱镜对红光和蓝光的折射率，则有：（ ）