Mark the letter A, B, c or D on your answer sheet to show the underlined part that needs correction in each of the following questions
If the oxygen supply in the atmosphere was not replenished by plants it would soon be exhausted
A. supply
B. was
C. by plants
D. exhausted
Đáp án là A. supply => supplying. Mệnh đê quan hệ rút gọn, vì ta thây có động từ “was”, câu không thể có hai động từ.