To express something that happened at an unknown time in the past; OR
To express something that began in the past and continues in the present.
1. Subject + have/has + past participle.
example: I have visited Hawaii.
explanation: You don’t know exactly when I visited Hawaii, but it happened sometime in the past.
2. Subject + have/has + past participle + for/since/all + time expression.
example: I have taught ESL since 2006.
explanation: I began teaching in 2006 and I’m still teaching.
*Exceptions about “unspecific” time:
You can use these time expressions to talk about something in the past with the present perfect tense: today, tonight, this week, this month, and this year.
Ex. I’ve already gone to the store today.
Past participles for regular verbs are the same as the past tense. (verb+ed)
Past participles for irregular verbs are usually different than the past tense.
(See Side by Side text p. 157 for an irregular verbs list.)
Negative sentences are similar, but we can add “not” or “never”. Subject + have/has +not/never + past participle.
examples: She hasn’t visited Hawaii.
She has never visited Hawaii.
Use “yet” (which means “before now”) only with questions and negative sentences.
examples: Have you done your homework yet?
No, I haven’t done my homework yet.
You can use “already” for positive statements. (This is optional).
examples: I’ve done my homework already. (I’ve already done my homework.)
You can use “ever” for questions. (optional)
example: Have you ever visited Hawaii?
In English we usually answer a question in the same tense that it is asked. When questions are asked in present perfect, an affirmative answer can be “Yes, I have.” When we give more specific details, we express that part of the answer with the past tense.
Past perfect tense (We’ll study this in Side by Side Ch. 8)
If you express something that happened (finished) in the past and say a specific time (like yesterday) or if you give specific details, you must use the past or past continuous tense.(See Side by Side textbook p. 40, 47 for examples.)
Example 1: Q: Have you gone to the bank? (present perfect)
A: Yes, I have. (present perfect short answer)
I went to the bank yesterday. (past tense due to specific time)
Neg: No, I haven’t. OR No, I didn’t. OR No, I haven’t gone yet. OR Not yet. OR No.
Example 2: Q: Have you gone to the bank? (present perfect)
A1: Yes, I’ve gone to the bank already. (pres perf can be used due to unspecified time)
OR A2: Yes, I went to the bank already. (past can also be used with an unspecified time)
OR Yes, I did. OR Yes, I already went. OR Yes, I went already. OR Yeah.
Notice the difference in meaning in these 3 statements:
I taught ESL for over 8 years. (past, finished)
I’ve taught ESL for over 8 years. (present perfect, still happening)
I’ve taught ESL. (present perfect, finished)
If something began in the past and continues now (in the present), you MUST use present perfect or present perfect continuous to talk about it.