I regret you that we are unable to offer you employment.
A. informing
B. having informed
C. to inform
D. to have informed
网友回答
A. informing
B. having informed
(答案→)C. to inform
D. to have informed
解析：考查regret的用法：regret doing后悔做过…,regret to do很遗憾要做…,句意是：我遗憾的通知你我们不能雇佣你。选C。