All passengers______go through safety check before they take a plane.
A. canB. may
C. mustD. ought
_____ carefully, Michael! There’s a school ahead.
A. DriveB. To drive
C. DroveD. Driving
Air pollution has become__________ than ever before. We must do something to stop it.
A. serious B. more serious
C. most serious D. the most serious
Old Mr. Black lives happily with his three dogs. of them are part of his family.
A. BothB. All
C. NoneD. Neither
—can you finish the report on food safety?
—In two days.
A. How far B. How much
C. How often D. How soon
The traffic is moving very slowly as so many carson their way back to Shanghai.
A. am B. is
C. are D. be
