which is 应该只是定语从句中才会出现He drove me around this small town which is quiet and beautiful.The teacher is late, which is abnormal because he's never late.如果是which +名词/代词+ Be， 就可以是名词性从句了。Which country you're from should not be a problem of preventing you from this health care program.It depends on which one of them you like best.
