[ 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:
Countable and Uncountable Nouns › Viewfire
A. countable
B. uncountable
Grammar › View
Change this sentence into passive!
A: Ahmad writes a letter
P: …………………………………………..
A. A letter is wrote by Ahmad
B. A letter are wrote by Ahmad
C. A letter is written by Ahmad
D. A letter are written by Ahmad
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
