16.1 Usage:
A: To describe an event, activity or situation that ended only a short time ago. Here the word just is often used.
e.g. I have just arrived home from work.
B: To describe an event, activity or situation that is to happen soon. Here, the word yet is often used.
e.g. I haven't telephoned her yet but I will telephone her before midnight.
C: To describe an event, activity or situation that began in the recent or long past and is still continuing.
e.g. Mary has always lived in France.
D: To describe an event, activity or situation with the meaning up to now.
e.g. I have never visited India but I hope to go there soon.
Have you ever met my brother?
16.2 Structure:
The general rule for the construction of the Present Perfect Tense of all verbs is:
Take the simple present tense of the auxiliary verb to have + the past participle of the verb:
e.g. My friends have gone to Provence for the weekend.
Bill has eaten five apples and three oranges today.
16.3 Structure: Negatives:
In negative statements, the word not is put immediately after has/have and before the verb:
e.g. I have not seen Martin this week.
/I haven't seen Martin this week.
16.4 Structure: Questions:
To form questions, reverse the positions of the auxiliary verb and the subject::
S AUX
e.g. Statement: John has worked hard all day.
AUX S
Question: Has John worked hard all day?