[ 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
Random Topics:
ApologizingCoherent Sentence with Correct Grammar StructureSimple, Compound, Complex SentencesModals and AdvicePresent Simple and Present Continuous TenseReported Speech and Reported QuestionsPast Perfect & Past Simplemust/shouldPrepositions of Place & TimeKnee AnatomyOther quiz:
Grammar › ViewWhich of the following is a proper noun?
A. city
B. dog
C. Paris
D. book
Grammar › View
Choose the correct conjunction to complete the sentence:
I couldn’t hear _____ could I see the speaker.
A. and
B. nor