6. As there is less and less coal and oil, scientists are exploring new ways of making use of energy, such as sunlight, wind and water for power and fuel.
| A．primary | B．alternative | C．instant | D．unique |
—I’ll tell Mary about her new job tomorrow.
—You ________ her last week.
| A．ought to tell | B．would have told |
| C．must tell | D．should have told |
On Sundays there were a lot of children playing in the park, and _______ parents were seated together joking.
| A．their | B．whose |
| C．which | D．that |
American people are wondering whether the newly-elected president and his administration will keep the nation safe and defend it _______ any terrorist attack in the future.
| A．to | B．on | C．against | D．with |
I’ll go to America to strengthen my English_______ it isn’t too expensive.
| A．except | B．provided | C．assumed | D．unless |
This January will be very precious for us by which time we______ reviewing Senior Book I.
| A．will finish | B．will have finished |
| C．have finished | D．will be finished |