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

Câu hỏi

If all countries to renewable energy, the environment cleaner.

A. switch/ will be

B. switch/ would be

C. switched/ would be

D. switched/ would have been

Đáp án
C. switched/ would be

Câu hỏi thuộc Bài tập:

If all countries __________ to renewable energy, the environment __________ cleaner.