They were principally used to catalyze aldol, allylation, Diels - Alder, ene and Friedel - Crafts reactions. 它们主要被用来催化Aldol, 烯丙基化, Diels-Alder, Ene和 Friedel -Crafts等反应.
He learned this lesson the hard way from his own personal experience.吃一堑长一智，他这个教训来之不易——是从他自己的亲身经历中得来的。The lesson from all of this is perhaps a broader one.从所有这一切中得出的教训可能具有更广泛的意义。It was the quickest swimming lesson I'...
贝蒂是吉姆的接生婆.Betty is the midwife of Jim.那个老奶奶做过接生婆.That old lady used to be a midwife.这个研究说仅仅 53% 的接生婆报告在报婴儿时用肥皂和水洗过手.The study says just 53 % of birth attendance ( attendants ) reported washing their hands with soap and d...