Polyacetylenes
多炔
🗣️ 情景例句
Seven letters ... two words ...
七个字母……两个字……
I wrote to him last Friday.
我上个星期五写信给他。
tap water that is too hot to touch can be left to cool and is generally safe to drink.
水管中流出的烫手的水可以留下来冷却。这种水一般是安全的。