[ Vocabulary ]
He then worked on peaceful applications of __________ that can substitute fossil fuel for a clean environment.
A. navigation
B. mantle
C. mutations
D. nuclear energy.

Random Topics:
Modals for Ability, Possibility and PermissionAuxiliary and Modal VerbsFirst Conditional & Future TensesModals and InversionPresent Simple and Past ContinuousTOEICVocabulary and IdiomsCountable - UncountablePast Tense, Recount Text, and Future TenseSuffixes and TensesOther quiz:
Past Simple › ViewThe baby ____________ (smile) at me an hour ago.
A. smile
B. smiled
C. smileed
D. smilied
Grammar › View
Where does the colon go?
A. These: are my favorite foods pizza, pasta, hamburgers and sundaes!
B. These are: my favorite foods pizza, pasta, hamburgers and sundaes!
C. These are my favorite foods: pizza, pasta, hamburgers and sundaes!
Past Tense › ViewAfter she …………………………. her breakfast, she went to work.
A. was eating
B. had eaten
C. ate
Grammar › View
There are a lot of tickets left, so you__________pay for the tickets in advance.
A. mustn’t
B. won’t
C. should
D. don’t have to
