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

The number of teachers volunteering in remote regions ______________ over the past few years.

A. is doubled

B. has doubled

C. have doubled

D. doubles

Đáp án
B. has doubled

Câu hỏi thuộc Bài tập:

E10- I-learn- Unit 6 (2)