Present Perfect Tense
作者：Yvvy Gamero
1. form
1.1. have or has + last form
1.2. have not (haven't) or has not (hasn't) + last form
1.3. Have or has ... + last form
2. last form
2.1. regular verbs: verb + ed
2.2. irregular verbs: last form of the verb (3rd form or past participle)
3. have or has?
3.1. I, you, we, they + have
3.2. he, she, it + has
4. use
4.1. action that is still going on
4.1.1. School has not started yet.
4.2. action that stopped recently
4.2.1. She has cooked dinner.
4.3. action that has taken place once, never or several times before the moment of speaking
4.3.1. I have never been to Australia.
4.4. finished action that has an influence on the present
4.4.1. I have lost my key.
4.5. puts emphasis on the result
4.5.1. She has written five letters.