They are used as auxiliaries to the present and past perfect tenses.
它们是用作现在完成时和过去完成时的助动词。
The present and past perfect tenses both belong to the perfect tense.
现在完成时和过去完成时都属于完成时态。
'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.
Ihave eaten是动词eat的现在完成时；Ihad eaten是过去完成时；Iwill have eaten是将来完成时。
So you learn the past tense and then two or three weeks later, oh now you are learning the present perfect, and then a few weeks later, you are learning the future, that's crazy.
你学习了过去时，然后两到三周后你开始学习现在完成时，几周以后你又开始学习将来时，这简直太疯狂了。
When we want to talk about actions or situations which started in the past and have continued up to the present, we often use the present perfect to show the connection between past and present.
要谈论行为或状态其始于过去而持续到现在，经常使用现在完成时表现过去和现在之间的连接。
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。
We use the present perfect tense to talk about things that started in the past and still have some connection with the present.
我们用现在完成时来谈论在过去开始并且仍与现在有联系的事情。
All the heavenly entities, the Amesha Spentas, instructed Zarathushtra in heaven, and he received perfect knowledge of past, present, and future.
所有的天体，AmeshaSpentas，在天上教导扎拉·图斯·特拉，他获得了过去，现在，未来的完美知识。
In English learning, it is difficult for learners to master the tense, especially the past tense and the present perfect tense.
英语学习中，时态的学习和运用对学习者尤其中低水平学习者来说是一个困难之处。
Comparison Compare the difference between the simple past tense and the present perfect tense.
现在完成时与一般过去时所表示的动作或状态都发生在过去，区别…
The present perfect simple is often used to talk about past actions and events which are completely finished.
一般现在完成时经常用于谈论过去的行为和事件其完全结束。
To grasp "the Present Perfect" and the Irregular verbs' past tense &past participle tense.
中文意思：掌握现在完成时态以及不规则动词的过去时态和过去分词…
The second function of the present perfect continuous tense is to talk about an action that started in the past and it is still happening.
第二种：谈论一个起始于过去，但是现在仍在发生的动作。
We use the present perfect tense to talk about an action that started in the past and continues to the present.
我们用一般过去时谈论发生在过去的动作和事情。
The present perfect is also used for long actions and situations which started in the past and went on until very recently.
现在完成时也用于长久的行为和状态其始于过去而持续到最近。
The present perfect is also used for long actions and situations which started in the past and went on until very recently.
现在完成时也用于长久的行为和状态其始于过去而持续到最近。
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