Câu hỏi :

The word those in paragraph 2 refers to__________.

A. bronchitis and asthma

B. carbon dioxide and nitrogen oxides

C. dangerous gases

D. respiratory diseases

* Đáp án

C

* Hướng dẫn giải

Dẫn chứng: Dangerous gases such as carbon dioxide and nitrogen oxides cause respiratory diseases, for instant, bronchitis and asthma. Those are also proved ....

Copyright © 2021 HOCTAP247