Computers must be of great use to ________ doing the scientific research.
| A．these | B．whoever |
| C．those | D．whomever |
Most companies’ marketing effort is focused on getting customers, with little attention _______ to keeping them.
| A．paying | B．to pay | C． paid | D．having paid |
Amazing! Too many private cars are trapped on the highways which is free of charge for the first time, causing heavy traffic jams, some even _______ for several hours.
| A．held up | B．broken up | C．taken up | D．given up |
—What do you think of Peter?
—He ______ be really difficult to get along with even though he’s a nice person in general.
| A．shall | B．should | C．must | D．can |
As the quality of the city’s air continues to give rise to ________, the residents are encouraged to drive cars less often.
| A．descriptions | B．compromise | C．concerns | D．emergency |
Not until the bus disappeared in the distance ________ her school bag was gone.
| A．Tina had found | B．had Tina found | C．did Tina find | D．Tina found |