—I knocked over my coffee cup. It went right over ____ keyboard.

—You shouldn’t put drinks near     computer.

A．the; 不填

B．the; a

C．a; 不填

D．a; a

缺乏维生素D，可导致家畜发生（）。

A.夜盲症

B.佝偻病

C.白肌病铁

D.脚气病