Polycyclic hydrocarbon
[机] 多核烃
🧩 词语组成解析
a. 多环的\\n[医] 多环的
🗣️ 情景例句
No. But I have to.
没有 ，但有此必要。
She's very well,thank you.
她很好，谢谢您。
Up to now, historians have assumed that calendars came into being with the advent of agriculture, for then man was faced with a real need to understand something about the seasons.
历史学家迄今认为日历是随农业的问世而出现的，因为当时人们面临着了解四季的实际需要，