'I have eaten' is the present perfect tense of the verb 'to eat', 'I had eaten' is the past perfect and 'I will have eaten' is the future perfect.

I have eaten是动词eat的现在完成时；I had eaten是过去完成时；I will have eaten是将来完成时。

《牛津词典》

A Spanish verb has six present-tense forms, and six each in the preterite, imperfect, future, conditional, subjunctive and two different past subjunctives, for a total of 48 forms.

西班牙语的动词现在时有六种形态，过去时、未完成时、将来时、条件句、虚拟句以及另外两种过去时虚拟式也各自有六种形态，加起来一共是48种。

youdao

To grasp the usage of the tenses, including the present, past, future tense and continue, perfect tense.

掌握现在时，过去时， 未来时， 进行时， 完成时的各种用法。

youdao

Success visioning involves asking a series of future, active, and past tense questions to imagine success in the future as if it has already occurred.

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And in doing so change the tense of American politics from the future to the past.

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Future, active, past tense questioning helps to paint the picture of success between the individuals involved, often uncovering expectations that would otherwise not see the light of day.

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