which可以指人吗？

从正规的语法来讲,引导词which who that是各司其职的
which只用于指物, who只用于指人,而that两者都可以指.
但社会在发展,语法也在不断发展,在口语中不会顾及这么多,但是在正规的书面表达上就一定要注意这些.
如果摸棱两可的时候,不如就用that,注意,当句子前面有逗号时就不能用that.

在www.google.com 打上 "which could be a person" （要加引号）可以查出两百多万条 我抄了其中一个供你参考。语言的特点都会遇到特列的，没有绝对的。

the system of the present invention includes a plurality of user stations each dedicated to servicing a user **** (which could be a person, another device, or machine)**** and each functioning as a stand-alone computer, having its own central processing unit, typically a microprocessor, and equipment by which the user can communicate with the central processing unit, typically a video display and keyboard terminal. The user stations may have other peripheral equipment as well, such as disk drives, printers, card readers, or the like. The user stations service the users by executing application programs supplied by the use