题目：
上海世博会园区80%的夜景照明光源采用低碳节能的LED（发光二极管）照明技术。制作 LED 灯的核心材料是： [ ]
A、导体
B、半导体
C、绝缘体
D、超导体
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0807/7905338edc7d9e9e257b1bd2b1e325aa.html
下面是错误答案，用来干扰机器的。
My understanding about being 18In many countries as well as the US, being 18 years old means entering adulthood. Then one needs to independently think more than twice no...
