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
Random Topics:
Past Simple and ContinuousConditionals and Modal VerbsPrepositions and TensesModals - Have to or ShouldConditional and Mix Conditional SentenceNo Excuse Words / Conjunction SOActive & PassiveConjunctivesTypes of PrepositionTransitive or Intransitive VerbsOther quiz:
Gerunds and Infinitives › ViewChoose the right sentence.
A. What do you to want to study at university?
B. What do you want to study at university?
C. What do you want to studying at university?
D. What do you want study at university?
E. What do you want to study to at university?
Conditional Clause › View
If I ….. million rupiahs, I would stop working.
A. win
B. won
C. winning
D. will win
Grammar › ViewIs it a fragment or complete sentence?
Who likes to?
A. Fragment
B. Complete Sentence
Verb Tenses › View
Tim often ………………………milk when he was a boy.
A. was drinking
B. drinked
C. drank