Câu hỏi: A chronic lack of sleep may make us irritable and reduces our motivation to work.

A. uncomfortable

B. responsive

C. calm

D. miserable

Câu 1: Population growth rates vary among regions and even among countries within the same region.

A. restrain

B. stay unchanged

C. remain unstable

D. fluctuate

Câu 2: We are very grateful to Professor Humble for his generosity in donating this wonderful painting to the museum.

A. meanness

B. sympathy

C. gratitude

D. churlishness

Câu 3: The works of such men as the English philosophers John Locke and Thomas Hobbes helped pave the way for academic freedom in the modern sense.

A. terminate

B. prevent

C. initiate

D. lighten

Câu 4: My cousin tends to look on the bright side in any circumstance.

A. be optimistic

B. be pessimistic

C. be confident

D. be smart

Câu 5: Solar energy is not only plentiful but also infinite.

A. without limit

B. boundless

C. limited

D. indefinite

Câu 6: In some Asian coutries, it is customary for people to worship their ancestors.

A. fossils

B. elders

C. heirs

D. forefathers