1.heat vt.& vi. 加热；变热；使温暖 n. 热，热爱
（1）Please heat the room, it’s too cold.
（2）The hall will not heat up easily.
（3）The sun gives us heat and light.
2. expand v. 扩大，增加，增强，扩展；
contract. v. 收缩，缩小，缩短；
Metals expand when they are heated.
Metals contract as they get cooler.
3. substance n. 物质
（1）What substance does it consist of?
（2）This is a chemical substance.
