David, get up early, ________ you’ll catch the early bus.
| A．but | B．and | C．after | D．or |
I hate people ______ talk much but do little.
| A．who | B．which | C．whose | D．whom |
—Could we go and watch the football game?
—No, ______ you have the tickets.
| A．if | B．unless | C．because | D．since |
—Can I go to the park, Mum?
—Certainly. But you ______ be back by six o’clock.
| A．can | B．may | C．might | D．must |
—I’m leaving now.
—______ you turn off the lights and the computer.
| A．To make sure | B．Make sure | C．Made sure | D．Making sure |
The population problem may be ______ one of the world today.
| A．the most | B．most difficult | C．the greatest | D．more interesting |