现在完成时

This is the status during the time when a checkpoint has not yet executed.

请问这句里的现在完成时是强调的还没有做过，还是没有完成？。。。

You don't need to know the rules for the present perfect tense.

你无需了解现在完成时的用法，你甚至可以不必知道"现在完成"是什么意思。

When do we use the past simple and present perfect?

我们什么时候使用一般过去时和现在完成时？

Make sure that you've mastered Present Perfect and Present Continuous in previous lessons.

确保你在前面的课程中已经掌握了现在完成时和现在进行时。

We use the present perfect tense to talk about things that started in the past and continue to the present.

我们用现在完成时来谈论一些过去的某一时间开始饿。而现在正在继续的事情

When he grew up, he worked as a sailor on a riverboat for some time and therefore he got his pen name, Mark Twain .

文章的时态主要用过去时，最后两句与现在有关，因此用了现在完成时和一般现在时。

If the past tense of the sentence adverb of time (eg yesterday, last, week, in 1960), you can not use the present perfect tense, use the past tense.

句子中如有过去时的时间副词（如 yesterday， last， week， in 1960）时，不能使用现在完成时，要用过去时。

After a further analysis, the two intralingual factors, verb salience and temporal adverbials, are found to significantly affect simple past and present perfect use and their tense marking.

通过测试动词突显度和时间状语两种语内因素对一般过去时和现在完成时的影响，发现他们能够显著影响其使用和时态标记。

Ed"词源解释:Etymology: Middle English, from Old English -ed,-od,-ad; akin to Old High German -t, past participle ending, Latin -tus, Greek -tos, suffix forming verbals

这个问题可能是属于语言学范畴了，请语言专家指点迷津。再比如，现在进行时为什么要加助词am，is，are；现在完成时为什么要加助词has，have？但这个问题我已搞清楚了。

From now on, we are going to study PRESENT PERFECT AND PAST.

从第一单元到第六单元，我们已经介绍了现在时与过去式，从现在开始，我们将进入学习现在完成时和过去式，OK，请往下看

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。