______many times, he finally understood it.
| A．To tell | B．Telling | C．Having told | D．Having been told |
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 |
—How did you get in touch with the travel agent, Robin?
—Oh, that’s easy. I surfed the Internet and then called one ________ the telephone
number is provided.
| A．which | B．in which | C．of which | D．whose |