present perfect

基本解釋

When you ask about something that started in the past but continues to the present time, you use the Present Perfect tense, e.g.
儅你談?wù)搹倪^去開始一直持續(xù)到現(xiàn)在的某件事時，用現(xiàn)在完成法時態(tài)。
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When you ask about something that started in the past but continues to the present time, you use the Present Perfect tense, e.g.: I’ve been there for 5 years / I’ve been there for 5 years.
儅你談?wù)撛谶^去開始但是一直持續(xù)到現(xiàn)在的某事時，用現(xiàn)在完成時態(tài)，例如：I’ve been there for 5 years/我在那裡已經(jīng)5年了。
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If we say when a past event happened (for example, by using time-adverbs), we do not usually use the present perfect.
說過去發(fā)生的事件（例如：用過去時間狀語），我們通常不用現(xiàn)在完成時。
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In grammar, the present perfect tenses of a verb are the ones used to talk about things that happened before the time you are speaking or writing but are relevant to the present situation, or things that began in the past and are still happening. The simple present perfect tense uses "have" or "has" and the past participle of the verb, as in "They have decided what to do."