He __________ on that invention for three years before he finally succeeded.
A. works
B. worked
C. has worked
D. had worked
Random Topics:
Simple Compound and Complex SentencesModal Verbs & Time PrepositionsModals in the PastPassive Voice & Verb TensesConjunctions, Interjections and Sentence TypeSubject and Verbs AgreementRelative ClausePrepositions after Verbs and AdjectiveModals for Necessity and SuggestionsGrammar - Present and Past PassiveOther quiz:
Vocabulary › ViewChoose the best antonym for the underlined word:
earnest about their health
A. serious
B. foolish
C. curious
D. worried
Vocabulary › View
What does the word ‘beckon’ mean?
A. To use your finger/hand to ask someone to come towards you
B. A man who’s never been married
C. A drink (of any type)
D. To come to an agreement about how much of one thing to exchange for how much of another
Conjunction › View______she went home, she realized that her house had been broken in.
A. As long as
B. As far as
C. As soon as
D. As well as
Vocabulary and Sentence Structure › View
The manager assigned a difficult task to the new employee. He completed it successfully.
A. Completing the difficult task which assigned by the manager was successful for the new employee.
B. After assigned a difficult task by the manager, the new employee successfully completed it.
C. The manager assigned a difficult task to the new employee, but he completed it successfully.
D. The new employee successfully completed the difficult task assigned by the manager.