Quote Originally Posted by meomok View Post
For me it will still sound good if you change the highlighted phrase into simple past. Though you you read the story again, it wouldn't emphasize that his/her friends have suggested such and such.

Apart from not indicating the time of the even, to me present perfect can also be used to emphasize that something has been done. Like in this situation here:
-Mother: Have you done your homework? (Con làm bài chưa?)
-Son: I have/ or I have already done my homework. (Con đã làm rồi)
The son doens't just want to say "I did my homework" because it wouldn't make as big an impact to his mother's question.
The son can answer grammatically: "I did my homework this morning" (if the question asked in the afternoon or in the evening)
More example:
_Did the postman come yet? (the question asked in the evening implies that whether he came in the morning)
Naturally, the people who is asked knows how to answer

_