'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》

Younger writers use more negative and past-tense words than older writers who use more positive and future-tense words.

年轻作家使用更多的否定式和过去式词汇，而年长的作家使用更多的肯定式和未来式词汇。

youdao

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

So can be changed slightly, depending on tense, past, present or future as well as whether or not you want to ask a question.

因此这个句型要根据不同的时态，如过去时、现在时和将来时，作出一点调整；另外也会根据是否是问句而略有不同。

There is 课堂 - SpeakingMax英语口语达人

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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Start by using future, active, past tense questions to define winning or excellence.

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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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