qua /kweɪ, kwɑː/●a sine qua ˈnon (of/for sth)BrE /ˌsɪneɪ kwɑː ˈnəʊn/ NAmE /ˈnoʊn/ (from Latin, formal) something that is essential before you can achieve sth else必要条件;必不可少的前提◆Many people believe that grammar is the sine qua non of language learning.许多人认为语法在语言学习中是必不可少的。NOTE In Latin, this means ‘without which not’.在拉丁语中,这个短语的意思是“必不可少”。