the form of the verb that is used to show that an action will have been performed by a particular time. In English it is formed by "will have" or "shall have" and a past participle

In the sentence "By that time I will have finished" the verb phrase "will have finished" is in the future perfect. 在句子 By that time I will have finished 中，动词短语 will have finished 用的是将来完成时。