b.inggris PRESENT PERFECT

Lesson Topic: Using The Present Perfect.

There are times when you are talking about an event in the past, but

you don't know when it happened, you don't care when it happened, or the time when it happened is a secret.

When talking about past events AND the time is unimportant, unknown, or a secret, the present perfect is a good tense to use. What is the present perfect? Here is an example:

I have visited 56 countries.

How is this grammar formed? It is formed with the following words:

I have visited 56 countries. subject + have or has + past participle

The past participle and the simple past are sometimes the same. Sometimes they are different. For the word visited, the simple past and the past participle are the same. If the simple past and past participle are different, they are usually irregular verb
The present perfect can give a starting time or an amount of time only if you use the words since and for. When using these words, the sentence usually means that the action is continuing. If you do not use since or for, the sentence means the action is finished, and it may or may not continue in the future. Take a look at these examples:

I have smoked. I have smoked for 12 years. NOT SURE it continues SURE it continues Meaning: The person smoked in the past (we don't know when), and he/she may still smoke, but we do not know. Meaning: The person started to smoke 12 years ago, and he/she still smokes.

Therefore, when the present perfect sentence does not have since or for, we do not know if it is still continuing.
So, the present perfect is used for one of the following two reasons:

1. When the time is unimportant, unknown, or a secret. OR 2. If the time is known and the action is continuing (for or since are used in this situation).

Some verbs are NOT used with for or since because they do not have any length of time. The following is a list of some verbs that can be used in the present perfect when the time is unimportant, unknown, or a secret. These words very rarely use for or since because they do not have a length of time. In other words, the following actions occur, but then almost immediately do not continue; they do not have a length of time. Therefore, they do not use for or since.

start arrive begin meet end leave stop

Here is an example of what we mean:

CORRECT We have begun the test. INCORRECT We have begun the test since yesterday.

The first sentence is correct because it does not use since or for. Begin (begun) does not have a length of time. After a few seconds, it is over; you cannot continuously begin the same test.
Some of you may know the present perfect progressive. If you do, then you may want to know what the difference is. For example,

present perfect I have worked here since 1977 OR present perfect progressive I have been working here since 1977.

Actually, there is little or no difference between these two sentences. You may want to know when to use the present perfect and when to use the present perfect progressive. We will continue this topic in our next lesson, but for now, remember this: the present perfect progressive almost always means it started in the past and is continuing; the present perfect means the action is continuing only if it uses since or for (otherwise, we are unsure if it is continuing). For example,

I have lived in Iran. Not sure if this person still lives in Iran; the time is also unknown. I have lived in Iran since 1997. We are sure this person still lives in Iran; we also know the time. I have been living in Iran since 1997. We are sure this person still lives in Iran; we also know the time.

The second and third sentences above have identical meanings. The first and second sentences have (potentially) different meanings even though they look almost the same.