The government _____ air quality in urban areas from level one to five: excellent, fairly good, slightly polluted, poor and dangerous.
| A． arranges | B．classifies | C．distributes | D．divides |
The weather turned out to be fine yesterday. I_____ the trouble to carry my umbrella with me.
| A．should have taken | B．could have taken | C．needn't have taken | D．mustn't have taken |
I was about to leave the office ______ an unexpected visitor came.
A. while B. as C when D. before
It was a matter of ________ would take the position.
| A．who | B．whoever | C．whom | D．whomever |
People try to avoid public transportation delays by using their own cars, and this ____ creates further problems.
| A．in turn | B．in all | C．take turns | D．by turns |
After the new technique was introduced, the factory produced_____ cars in 2008 as the year before.
| A．as twice many | B．as many twice | C．twice as many | D．twice many as |