The manager promised to keep me_______ how our business was going on.

A.informing of

B.informed of

C.to inform of

D.on informing

答案：B

考查固定结构。Inform sb of sth通知某人某事;sb与inform构成被动关系，所以形成keep sb informed of sth通知某人某事;句意：经理答应通知我生意的进展情况。