单选题 I regret ______ the work unfinished; I should have planned everything ahead carefully.
A. having been left B. having left C. to leave D. to have left

【正确答案】 B

【答案解析】[解析] 本题考查动词regret后接动名词或不定式的用法。regret doing：后悔做某事，用完成时表示已经发生过的事情。regret to do：很抱歉要做某事。