(used with past participle to form perfect tenses 与过去分词构成完成时态)： She has finished the novel. 她已经读完了那本小说。I had not seen her at least one week by then. 那时我至少有一周没见到她了。They will～fulfilled the production quota by the end of this month. 到本月底，他们将会完成生产定额。Jennie has been working all day. 珍妮整天在工作。You ought to～noticed it. 你本应该注意到这一点的。If I had known (Had I known)， I would～told you. 如果我当时知道，我就告诉你了。