--Would you please explain to me about the difference between the two phenomenon?
--I’m sorry, but that’s just _____ I’m puzzled about.
| A．why | B．what | C．which | D．where |
The factory ___ I am going to is the place ___ my mother used to work many years ago.
| A．where, where | B．where, which | C．which, where | D．that, which |
The last river __ _ they crossed is two miles wide.
| A．where | B．which | C．that | D．in which |
This is one of the means ____t he electic energy is conducted from one place to another.
| A．by which | B．by that | C．through which | D．through that |
The buses, ____were already full, were surrounded by an angry crowd.
| A．most of them | B．most of which | C．which most | D．that most |
Can you solve such problems ___raised by the audience?
| A．what were | B．as were | C．that were | D．which were |