The old man _____ chess but now he doesn’t enjoy it.
| A．used to play | B．used to playing |
| C．was used to play | D．was used to playing |
I hope that the little ________ I have been able to do does good to them all.
| A．which | B．what | C．that | D．when |
I hope that the little ________ I have been able to do does good to them all.
| A．which | B．what | C．that | D．when |
There are several research centers in China ________ a certain disease called Bird Flu is being studied.
| A．which | B．where | C．when | D．what |
The treatment will continue until the patient reaches the point ________ he can walk correctly and safely.
| A．when | B．where | C．which | D．whose |
October 15 th is my birthday, ________ I will never forget.
| A．when | B．that | C．what | D．which |