[ Tenses ]
The fossil fuels ____ air pollution significantly last century.
A. contributed
B. contribute
C. is contributing
D. will contribute

Random Topics:
The Past SimpleComparisionModals and Active and Passive VoicePresent Simple PassiveInfinitive and GerundsCorrelative ConjunctionFuture Tense - will and going toAdjectives Ed and IngContinuous and Perfect TensesArticleOther quiz:
Conjunctions › ViewThomas doesn’t play the guitar, __________ he plays the drum.
A. and
B. but
C. so
D. because
Tenses › View
Which tense is used to describe an action that will definitely happen in the future?
A. Future Simple
B. Future Perfect Continuous
C. Future Continuous
D. Future Perfect
Passive Voice › ViewUp to now, the equipment ____ regularly, but from now on, we ____ it before every outing.
A. wasn’t checked – are checking
B. hasn’t checked – will be checking
C. hasn’t been checked – are going to check
D. isn’t being checked – should be checked
Basic Grammar › View
The plane arrived (…) the airport just on time.
A. on
B. of
C. at
D. by
