单选题 But for your help, I ______ the task by myself, so many thanks to you.

【正确答案】 D
【答案解析】[解析] 本题考查虚拟语气。but for意为“要不是”，常引导与过去事实相反的条件状语，句子用虚拟语气。主句用would/ should/could/might have+动词的过去分词，should只用于第一人称。