--- Had we been more careful, the accident might not have happened.
--- But we _____ at that time.
| A．hadn’t | B．didn’t | C．weren’t | D．might not |
I'm afraid he's more of a talker than a doer，which is ________ he never finishes anything.(2011·山东)
| A．that | B．when | C．where | D．why |
I'd like to start my own business—that's ________ I'd do if I had the money.(2011·江西)
| A．why | B．when | C．which | D．what |
Scientists study ________ human brains work to make computers.
| A．when | B．how | C．that | D．whether |
We promise ________ attends the party a chance to have a photo taken with the movie star.
| A．who | B．whom | C．whoever | D．whomever |
The newcomer went to the library the other day and searched for ________ he could find about Mark Twain.
| A．wherever | B．however |
| C．whatever | D．whichever |