Present Perfect vs. Simple Past

If the time of the action is not important or not specified, you should always use the current perfection

When describing and requesting details of when and where action occurred, you must always use a simple past.

There are differences in attitudes between the two tenses. This is usually an important factor in choosing which tense to use.

"What did you do at school today?" The issue concerns activities, school days are considered perfect, so I will use a simple past tense.

"What did you do at school today?" Because the question concerns the results, I now use perfection. Time to ask questions is considered a continuation of school day.

Although the two formats are not usually interchangeable, the current full meaning (what happened before the present time) is similar to the past simple meaning. The past time frame is a simple past used in the past. It is perfect right now. See the related section below for details. For all uses of a certain perfect structure, please see below for the perfect part of the present perfect past, the perfect future of the past

In British English, the use of Simple Past and Present Perfect is very strict. Given past time expressions, you must use simple past. If you do not have a word to draw attention, you need to decide whether you are talking about past actions or whether the result is important.

The simple past closely resembles the current full meaning. The simple past is used (ie, it does not last until the current time) if it is considered that an event will occur during a specific time in the past, or a period that ended in the past. This time range can be stated or implied explicitly in the context (eg past time series are often used when describing past event sequences). In some cases past simplex is also used without prior quotation. Subordinate phrases including conditional phrases and other hypothetical situations (see the conditional § note and § dependent clause below). After expressing wishes. For past virtual tone (instead of yes), see the subjective mood of English. For indirect conversations and past uses in similar situations, please refer to the following indirect voice.

When a verb wants to manage a phrase, when the desire to express includes the current state, the past completeness (or the integrity of the past), when it contains a past (usually different from the fact) past tense Simple past or past progressive) conditions or events and simple conditions as it becomes desirable current behavior or country change. For example, the form of a verb that is not included in any of the above rules (which the verb passed perfectly or formed a level or other style with no equivalent meaning) will not be changed. Note that the application of the above rules is not mandatory; sometimes the original verb tense is retained, especially when the statement (including the original tenses) is equally valid at the time of reporting.