Câu hỏi :

Read the passage and choose the best answer.

A. It takes the place of a radio. 

B. It has improved navigational safety. 

C. It was developed from a study of sound waves. 

D. It gave birth to the invention of the airplane.

* Đáp án

B

* Hướng dẫn giải

Dựa vào “Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.”

Đáp án  B

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