[ Grammar ]
Nobody knows for sure, but it’s believed that the balls ___ by the ancestors of native people.
A. could have been made
B. could be made
C. could have made
D. could have be made

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Possessive AdjectivesConnectives (because, due to, owing to, because of)Perfect and Past TensePreposition FormZero & First ContidionalPast and Present Continuous tenseAdjectives and AdverbsSubjective and Objective PronounReflexive pronounsTenses: Present simple, Past Simple, Future SimpleOther quiz:
Prepositions of Time & Place › ViewIt happened ____ September 2001.
A. in
B. on
C. towards
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Grammar › View
Helen, together with her brothers, _________ leaving the country this Friday.
A. am
B. are
C. is
D. were