We can never expect________bluer sky unless we create________less polluted world.
| A．a; a | B．a; the | C．the; a | D．the; the |
-- Are you free now? I have something interesting to tell you.
--- OK, _____ you make it short. You know, I am busy.
| A．now that | B．as soon as | C．every time | D．as long as |
My mobile phone is missing. Who _____ it?
| A．must have taken | B．should have taken |
| C．could have taken | D．need have taken |
The young man, _____ in heavy traffic on the way, got home an hour later than usual.
| A．catching | B．caught | C．having caught | D．to be caught |
Don’t run red lights, _____ you may get run over by a car.
| A．so | B．but | C．for | D．or |
Language is changing all the time. Some English words today can mean totally different things to _____ they meant before.
| A．which | B．that | C．不填 | D．what |