Listens to some friend's message, said you already began school, really envies oh, ha-ha.

听一些朋友的留言，说你们已经开学了，真羡慕哦，呵呵。

youdao

The-COOH contents in HA increases, phenolic-OH group decreases and the chemical acidity of acidic functional groups increases when HA is oxidized by nitric acid.

用硝酸氧化能使ha中羧基含量增加，酚羟基减少，酸性功能团活性提高。

youdao