As coal mines became deeper, the problems of draining water, bringing in fresh air, and to the surface increased. A. how ore is transported      B. transporting ore C. ore is transporting  

As coal mines became deeper, the problems of draining water, bringing in fresh air, and ______ to the surface increased.
A. how ore is transported
B. transporting ore
C. ore is transporting
D. to transport ore

Trả lời
Đáp án: B

Câu hỏi cùng chủ đề

Xem tất cả