[ Tenses Usage ]
The scientist _____ solutions to clean polluted rivers when she discovered a breakthrough.
A. researched
B. was researching
C. had researched
D. is researching
Select your answer:
Random Topics:
Direct and Indirect SpeechPresent Simple Affirmative and NegativeBe used to vs used toThere is, There are, Some, AnyPreposition and Preposition PhraseModals of ProhibitionThe Simple Present TenseModals of AdviceGrammar, Literature, and VocabularyOther quiz:
Grammar › ViewIdentify the part of speech of the given word.“beautiful”.
A. Adverb
B. Noun
C. Verb
D. Adjective
Pronoun-Verb Agreement › View
The dog and cat ____ outside.
A. play
B. plays