Polyfluoride
多氟化物
🗣️ 情景例句
autograph copies for the guests at the opening?
在展览开幕时为客人在书上亲笔签名呢
You cannot make a silk purse out of a sow's ear.
猪耳朵做不成丝钱包；巧妇难为无米之炊。
Look at this letter from Wang Wei to her penfriend in Australia.
请看这封王伟写给她在澳大利亚的笔友的信。