Mark the letter A, B, C or D to indicate the correct answer to each of the following questions.

Câu hỏi

All the different plants and animals in a natural community are in a state of __________.

A. peace

B. balance

C. energy

D. pollution

Đáp án
B. balance

Câu hỏi thuộc Bài tập:

Ms. Dung Purple - Unit 9: Protecting the Environment - Vocabulary