单选题 I ______ have written to him because he phoned me shortly afterwards.
A. needn't B. oughtn't to C. wouldn't D. shouldn't

【正确答案】 A

【答案解析】[解析] needn’t have done sth．表示过去做了某事．但事后证明没有必要做。oughtn’t to/shouldn’t have done sth．表示过去做了不该做的事。’wouldn’t have done sth．用在虚拟条件句过去时的主句中，表示如果具备了所指的条件就不会做某事。