Quadrivalence
n. 四价\\n[医] 四价
🗣️ 情景例句
Well, we do too, Ellen.
嗯， 我们也需要，Ellen。
I'm up to my ears in work.
我忙死了。
It is hard for us to realize nowadays how difficult it was for the pioneers.
我们今天很难想像昔日的登山先驱们是多么艰苦。