After retirement, learning a musical instrument may be harder than ______ when you were a kid.
| A．it may | B．it was | C．it does | D．it did |
Do you know the year ________ the Chinese Communist Party was founded?
| A．which | B．that | C．when | D．on which |
This is the hotel ________ last month.
| A．which they stayed | B．at that they stayed |
| C．where they stayed at | D．where they stayed |
Do you know the man ________？
| A．whom I spoke | B．to who spoke |
| C．I spoke to | D．that I spoke |
The place ________ interested me most was the Children's Palace.
| A．which | B．where | C．what | D．in which |
________ we have enough evidence，we can't win the case.
| A．Once | B．As long as | C．Unless | D．Since |