which 
英 [wɪtʃ]  美 [hwɪtʃ] 
pron. 哪一个，哪些

adj. 哪一个，哪一些

例句：
Which picture do you want? 

你要哪幅画？

Which flavour do you want? 

你想要哪种味道？

I can't remember which teachers I had. 

我记不起来哪些老师教过我了。

Scientists have long wondered which parts of the brain are involved in musical tasks. 

科学家们一直想知道大脑的哪些部分是用来处理音乐的。

Which of these are yours? 

这里面哪些是你们的？

Tell me which you want. 

告诉我你想要哪个。