Facebook has become one of the most popular social websites. Its founder __________ when he started it years ago.
| A．could never imagine it |
| B．must never have imagined it |
| C．must never imagine it |
| D．could never have imagined it |
I know a little bit about the city as I __________ there for one year in my youth.
| A．am studying | B．had studied | C．studied | D．have studied |
While working in the countryside, the students a great deal of knowledge on plant life.
| A．looked up | B．picked up | C．put up | D．called up |
Criticism and self-criticism _____ necessary _____ it helps us to correct mistakes.
| A．is, in that | B．are, in that | C．is, in which | D．are, at that |
Running a company is not _______ a matter of hiring people — they also need to be trained.
| A．simply | B．partly | C．seriously | D．equally |
—What made ber so sad? —______a good chance to go abroad.
| A．Miss | B．Missed | C．Missing | D．Being missed |