Polyacetylenes
多炔
🗣️ 情景例句
Thank you very much.
谢谢你。
Mrs.Jones,this is Mr. John Smith.
琼斯夫人，这是约翰、史密斯先生。
it is quite reasonable to regard the sea floor as the basic form of the crust of the earth,
因此完全有理由把海床看作地壳的基本模壳，