Select your answer:
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Grammar: Imperative and Exclamatory SentencesRegular and Irregular VerbsIf ConditionalsArticles and QuantifiersTypes of Sentence StructuresPrefixes SuffixesSimple Present Tense with Adverb of FrequencyGrammar - could / could notInfinitives and GerundsPresent ContinousOther quiz:
Tenses › ViewWhat ______ you ______ (do) at 8 PM yesterday?
A. was, doing
B. were, doing
C. are, doing
D. do, do
Modals › View
Using lasers to produce extremely short and repeatable pulses of light, today scientists ———— events happening in time intervals as short as l.000 trillionth of a second.
A. must have measured
B. were measuring
C. used to measure
D. may have measured
E. are able to measure