is this reading-room the one _which/that you once studied in?
填which/that 均可。其它的就不成了。定语从句规则多,不是一两句说得完。
我是英语教师,你有不明的可问我。
which
in which
that不可以用在介词后
you once studied in 这里有in 只能用which
the one不会影响是选which还是that,不过对这个从句有很多的影响,因为这就是定语从句的先行词。
我记得是如果介词在先行词后,紧接着只能用which。如:the one in which you once studied.
但是如果介词在后面的话(像你举的例子),两者都可以