Polybutadienes
(polybutadiene 的复数) [机] 聚丁二烯
🗣️ 情景例句
Typing is easy once you get the hang of it.
一旦你掌握诀窍，打字就很简单。
He has been to America.
他去过美国。[曾经有过的经验]
He quickly became the leader.
他很快就成了领袖。