—Remember this, children. _______ you study, _______ knowledge you will get.

—We know, Mr. Green. [ ]

A. The harder, the less

B. The hard, the more

C. The harder, the more

D. harder, more

造成煤气炉炉箅烧坏的最直接原因是（）。

A.风量用量过大

B.火层上移

C.火层下移