Câu hỏi :

The word "they" in paragraph 2 refers to ______.

A. predators

B. humans

C. cities

D. foods

* Đáp án

B

* Hướng dẫn giải

Dẫn chứng: ...so it was not until humans began to practice agriculture that they were able to gather in large enough numbers to form cities.

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