Câu hỏi: The developing of the submarine was hindered by the lack of a power source that could propel an underwater vessel.

A. developing

B. the

C. a power

D. could propel

Câu 1: Ours brains are incredibly agile machines, and it's hard to think of anything they do more efficient than recognize face.

A. are

B. anything

C. efficient

D. recognize

Câu 2: The notion that students are not sufficiently involved in their education is one reason for the recently surge of support for undergraduate research.

A. notion

B. are not

C. their education

D. recently

Câu 3: Not one in one hundred children exposed to the disease are likely to develop symptoms of it.

A. not one

B. are

C. symptoms

D. it

Câu 4: A beaver uses its strong front_teeth to cut down trees and peel_off its bark.

A. its

B. front teeth

C. eel off

D. its

Câu 5: Today, although their status varies from country to country, women in most parts of the world have gained significance legal rights.

A. although

B. most parts

C. gained

D. significance

Câu 6: The clerks who are happy to wait for their customer will get promoted soon.

A. clerks

B. wait for

C. customer

D. get promoted