The manager promised to keep us of how our business was going on.
A. being informed
B. informed
C. informing
D. to be informed
网友回答
A. being informed
(答案→)B. informed
C. informing
D. to be informed
解析：句意：经理答应让我们及时了解我们的生意进行的情况。inform sb of sth告诉某人某事；其被动：sb be inform of这里是keep sb done,这里sb与do之间是被动关系，故选B。