which???

基本可分２種．
作為問題時，ＷＨＩＣＨ是在固有選擇中（可以超過２種）選擇，比如Which one do you prefer? Which color do you like better? 但，由於目前在conversation 中大部分人都會用what 去問一些選擇的問題，比如What is your blood type? What is your favorite color?所以，一般情況下，可以按照問題方式去用，比如：What is your blood type? Which blood type are you?

另外，作為ＰＲＯＮＯＵＮ，就是在２句中間的連結，比如He is driving the family car, which
has been in his possession since his father passed away. "which" 指的就是那架車．作為
pronoun時，簡單的說，只能指死物或抽象的concept, 比如，He delivered a speech which
was not very well received by the audience. My boss approved my proposal, which means
that we can now go ahead with the project.