Heptaoxacycloheneicosane
[化] 七氧代环二十一烷; 21-冠-7; 21-冠醚-7
🗣️ 情景例句
I am planning to write an editorial that I think will help you.
我计划写一篇社论， 我认为应该能帮助你们。
I won the most valuable prize!
我赢得了最高的奖赏！
I was very tired when I arrived home. I'd been working hard all day.
我到家时非常累。我一整天都在玩命地干！