Unipolycondensation
单一缩聚作用
🗣️ 情景例句
But personally I believe a business letter should end with Very truly yours, not Sincerely.
还行，乔治。但是我个人相信一封商业信函应该以“敬上”结尾，而不是“谨启”。
Skiing is such a difficult sport that it's more work than play.
滑雪是非常困难的运动，真所谓工作高于游戏呀。
Then they had a second child-a son. How happy they were!
后来他们有了第2个孩子一个儿子。他们多么高兴啊！