Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

Tim asked Sally _____________ English so far.

A. how long was she learning

B. how long she has been learning

C. she had been learning how long

D. how long she had been learning

Thế nào là bản vẽ chi tiết? Bản vẽ chi tiết dùng để làm gì?