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One of _______ most serious environmental problems is _______ pollution.
A. the,zero
B. a,the
C. an,the
D. zero

Random Topics:
Prepositional PhrasesSo or SuchConditionals / Unreal PastPunctuationsModal Auxiliary VerbsSubjective and Objective PronounCoordinating & Subordinating ConjunctionsComparison Degree & GerundsSo / Neither / Either / TooSubjunctiveOther quiz:
Tenses › ViewThey ___ TV when we arrived.
A. were watching
B. watched
C. had watched
D. watch
Gerunds › View
Sharon doesn’t like ….. by bus.
A. driving
B. flying
C. running
D. traveling
Grammar › ViewWhat is the correct spelling of chop + -ed?
A. choped
B. chopped
C. chopt
Passive Voice › View
What is the important rule in Passive Voice?
A. V1
B. V2
C. V3
D. V-ing
