题目

Bedazzling （眼花缭乱） with their bright colors and eye-catching displays, fireworks light up our night skies during the holidays．However, these crowd-pleasers can have some damaging side effects． Once a firework is set off, it only takes a couple of seconds before smoke, dust and harmful chemicals are let out into the atmosphere．The loud booming noises are caused by gunpowder．While the sounds may excite some people, they can be frightening to domestic and wild animals—as well as some humans． The pretty colors you see are a result of more chemicals．Barium, added to make 两正方形的周长比为，则相似比也为． (　　)