1·'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》
2·Present Perfect Tense.
现在完成时。
3·To grasp the usage of the present perfect tense.
掌握现在完成时态的用法。
4·Talk about the uses of the present perfect tense.
表示过去发生的事对现在仍有影响。
5·French tense to the present perfect tense in English.
法语中没有和英语的现在完成时完全对应的时态。
6·You'll be able to use the present perfect tense for checking up.
你可以用现在进行时态去检查。
7·In this lesson, we will practice using the present perfect tense.
在这节课上，我们将要练习使用现在完成式。
8·It is not easy to learn to use the present perfect tense correctly.
学习正确使用现在完成时不是容易的事。
9·Fill in the blanks with the present perfect tense of the verbs in brackets.
用括号里动词的现在完成时态来填充空格。
10·The present perfect tense emphasizes the effect of the past action on the present.
现在完成式强调过去所发生的事情对现在的影响。