They are all() 为什么此题不是 mathematic teachers而是 mathematics teachers呢?

They are all() 为什么此题不是 mathematic teachers而是 mathematics teachers呢? （They ）are all in school.为什么填they. Are they all right They are all right. Are they all right? where are they all they are ____students.A.both B.all选哪个?为什么? 【高中英语】代词用法______ of the three students can repair your computer.They are all experts.此处为什么填whichever而不用which? they are all old ones 的ones在此句中为什么是表语? they all are friend 还是 they are all friend They are all 17.还是They all are 17. They are all yellow 如上 They are all working ____.. They are all ____(price). They are all my ----------(cousin) They are all my loves all things are difficult before they are all things are difficult before they are