I have a pencil box. It's blue. There are lots of things in it. I have a pen. It's red and long. I like it. I have three pencils. They are short. I have a ruler. It's big. I have an eraser. It's small.

以下对电磁波的认识，正确的是（　　）

2.4米：60厘米化成最简单的整数比是____，比值是____。