essential
A. biodiversity
B. temperate
C. instrumental
D. conservation

Random Topics:
PrepositionsModal Verb in Passive VoiceConjunctions, Interjections and DeterminersVerb Tenses and ModalsDegrees of ComparisonVerb TensesCommasComparative and Superlative AdverbsPronouns/ Present TenseGoing To Be and WillOther quiz:
Vocabulary › ViewWhich of the following sentences uses the word “ambiguous” correctly?
A. The instructions were ambiguous, so everyone understood them clearly.
B. Her ambiguous statement made me question whether she could be trusted.
C. The ambiguous weather was perfect for a picnic.
D. He was ambiguous about his favorite color.
Grammar › View
Should _____ help keeping their weight, blood pressure, pulse, and cholesterol down, swimming is an excellent activity.
A. adults need
B. needy adults
C. to need
D. need adults
Phrasal Verb › ViewDon’t _____________! If you keep practising, you will be a great basketball player someday.
A. take up
B. show up
C. pick up
D. give up
Modal Verbs › View
Did Peter go downtown by car or by train?
He … by train, because his car was in the mechanics.
A. must go
B. has to go
C. had gone
D. must have gone