_____ your attention focused on practicing, and you can reach your goal of becoming an excellent pianist.

A．Keep

B．Keeping

C．To keep

D．If you keep

电炉倾动机构（EBT炉除外）应使炉体向炉门方向能倾动（）度，以便于扒渣等操作。

A．30°

B．10°～15°

C．45°～45°