PRESENT SIMPLE VS. PRESENT PERFECT

DIFFERENCES BETWEEN SIMPLE PRESENT AND PRESENT PERFECT

 

The present simple is used about something going on when you speak, Present perfect is used about something already finished, but that still has a special importance when you speak. Example of present: Now I fry the chicken for us. Example of present perfect: I have just fried the chicken, The last sentence signals that it is ready to be eaten, which is the important aspect. Usually the important aspect is a state that the action produced.

But the English present perfect tense is also used about an action that began in the past, but still is going on, for example: I have attended law school for two years now. In this case it does not really function as a real present perfect.
The present perfect refers to an act that took place in the past, from the perspective of the present. "I have eaten" means that at some point in the past, eating occurred. Now (at the present), it is over.

The simple present tells you about what's going on currently. "I eat" means that the act of eating is ongoing. (Though it can also refer to a habitual act; I may not be eating right at this instant, but it's the sort of thing that I could be doing right now, because the eating isn't complete.)

In general, the tense of the sentence tells you what time the sentence is pointing to, and the perfect aspect tells you that the act was done before that. So the past perfect "By six o'clock, I had eaten" means that at some point in the past (6:00), some eating event had already been completed (before 6). It's the past perfect because "had" is in the past. "I have eaten" is present perfect because "have" is present. It's "perfect" because the act is over.
 
Present Tense usually talks about routine actions, such as: I go to work every day, or I work twice a week, etc.

Present perfect tense talks about actions that has happened in past with in unspecified time frame, such as; I have eating carrot cake or I have met CEO of Nike, or I have gone to the concert. etc.

The present perfect is pretty complicated, one of the more difficult tenses in English to use correctly. It is used for actions that happened in the past but with results that continue to affect the present.  It is usually signaled by one of the following contexts:
1.  ever or never    Have you ever been to France?
2. already or yet   I have already eaten dinner.
3. since (a point in the past)    I have lived here since 1995.
4. for (a length of time)            I have lived here for 20 years.
5. action that occurred a number of times      I have been to France 5 times.
6. just or recently              I have just eaten dinner.

The simple present is used in situations where the action continues to occur repeatedly in the present:  I eat dinner at 6:00 every night.