—Clover, why didn’t you attend the meeting yesterday?
—I ____, but something unexpected happened．
| A．had | B．would | C．was going to | D．did |
It was in the street ______ I live that I met Mr. Green.
| A．that | B．which | C．where | D．when |
A man may usually be known by the books he reads _______ by the friends he keeps.
| A．as well as | B．as if | C．as soon as | D．as usual |
There are so many books! It is not easy for us to decide what to take and what to_______.
| A．take on | B．pick up | C．leave behind | D．work out |
When I try to understand _______ that prevents so many Americans from being as happy as one might expect, it seems to me that there are two causes.
| A．why it does | B．what it does | C．what it is | D．why it is |
The science of medicine, _______ progress has been very rapid lately, is perhaps the most important of all the sciences.
| A．to which | B．in which | C．Which | D．with which |