We first met on a train in 2000．We both felt immediately that we _____ each other for years.
| A．knew | B．have known | C．had known | D．know |
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 |
His writing is so confusing that it's difficult to make out ________ it is he is trying to express.(2011·安徽)
| A．that | B．how | C．who | D．what |