题目

If you want to learn anything at school, you need to listen to your teachers. Unfortunately, millions of kids can’t hear what their teachers are saying. And it’s not because these students are goofing off. Often, it’s the room’s fault. Building architecture and building design can create echo(回声)-filled classrooms that make hearing difficult. Children with hearing impairments（损伤）suffer most from noisy classrooms. They sometimes can’t hear questions that other students ask in class. Compared with kids with healthy hearing, they have a harder time picking up new vocabulary 下列物质由原子构成的是 A．石墨 B．氯化钠   C．二氧化碳 D．C60