Other experiments were undertaken in Europe and America, but the arc light eventually proved impractical because it burned out too quickly.

Câu hỏi :

Other experiments were undertaken in Europe and America, but the arc light eventually proved impractical because it burned out too quickly.

A funded                     

B discovered                

C failed                        

D carried out    

* Đáp án

D

* Hướng dẫn giải

Phương pháp giải:

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