He is brave hard-working and kind so he was elected monitor of our class.A. as a B. /C.

问题补充：

He is brave, hard-working and kind, so he was elected monitor of our class.

A. as a

B. /

C. a

D. to be the

答案：

A. as a

(答案→)B. /

C. a

D. to be the

解析：表示独一无二的职位、头衔的名词在句中作表语、补足语、同位语时，不用冠词。