Example 1: I have already asked my mom, so I can go to the park.
We use "already" for positive statements in the present perfect tense.
The past participle (P.P.) "asked" is the same as the past tense form for regular verbs.
Use "have" or "has" before the P.P. to make the present perfect tense.
Example 2:
John has just finished his homework.
We use "just" to talk about an action which happened a short time ago.
Example 3: Have you called your friend yet?
Example 4: I have not fried the noodles yet.
We use "yet" to ask a question and to make a negative statement in the present perfect tense.
We use "since" in a present perfect tense sentence to mention the starting point of the time the action happened.
I have studied English since 2008.
We use "for" to mention the length of time the action happened until now.
Example 5:
Jeff has chopped vegetables for three hours.
