Polyacetylen
聚乙炔; 聚乙炔
🗣️ 情景例句
and make sure that it is in good condition
确定它状 良好
When's class gonna end?
怎么还不下课？
(remember how easily the Apollo astronauts bounded along),
还记得阿波罗飞船中的宇航员轻松地跳跃-