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

He wondered ______________ he had left the key at home.

A. if not

B. whether

C. unless

D. in case

Đáp án
B. whether

Câu hỏi thuộc Bài tập:

E10- I-learn- Unit 5 (2)