Câu hỏi: Deserts often include _________ and rocky surface.

A. oil

B. water

C. sand

D. trees

Câu 1: Do you know how many countries __________ part in the sporting event?

A. take

B. make

C. have

D. do

Câu 2: He is one of the most ………. bosses I have ever worked with. He behaves rudely to not only me but also others in the staff.

A. thoughtful

B. impolite

C. attentive

D. communicative

Câu 3: Whenever problems come up, we discuss them frankly and find solutions quickly.

A. happen

B. encounter

C. arrive 

D. clean

Câu 4: Although the staff did expand somewhat for the first century of its existence, the entire teaching staff consisted of the president and three or four tutors.

A. to and from

B. more or less

C. back and forth

D. side by side

Câu 5: ______- is natural environment in which plant or animals live.

A. Ecology

B. Habitat

C. Extinction

D. Biodiversity

Câu 6: Many plants and animal species are now on the _______ of extinction.

A. danger

B. border

C. margin

D. verge