Present Perfect Tense is use to express action that happened at an unspecified time before now. The exact time is not important.
The formula for Present Perfect Tense:
S + have/has + Past Participle (Verb3) + Object (The Object can be already or yet)
1. I have done my homework already
2. She has eaten breakfast
3. I haven’t done my homework yet
4. Has she had breakfast yet?
5. What have you done already?
6. Who has been seen by her?