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I learned that historical event like "Korean war broke out in 1950." should be described with past tense.

But when a past event influences present situation, could we use 'present perfect'?

Like this,'Korean war has broken out in 1950.' or 'Edison has invented the electric bulb.'

please, tell me.

marked as duplicate by GoDucks, JMB, Chenmunka, stangdon, Peter Jan 6 '16 at 17:14

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  • Please choose more specific tags for your posts. "Grammar" is too generic for this post, while "Present-perfect" is, well, perfect. – CowperKettle Jan 6 '16 at 10:51
  • The general rule is that then a "specific time expression" like "in 1950" is present in the clause, you should not use the Present Perfect, and opt for the Simple Past instead. Note that's there's a seemingly counter-intuitive use of the Present Perfect inside "since"-clauses - see this post and Swan's Practical English Usage, Unit 522.3 (kudos to Damkerng). – CowperKettle Jan 6 '16 at 11:43
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    Duplicate of your own previous question Can we use the present perfect in this case?. I think you really ought to edit your previous question to include the new example (Edison has invented the light bulb) but that question would be a duplicate of The Chinese have invented the electric bulb. – GoDucks Jan 6 '16 at 15:53
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The simple past tense conveys the idea that the action described was completed in the past; it is over and done with. With the simple past, there is no expression of a relationship with, or bearing upon, the speaker's sense of The Now.

The present perfect expresses some relationship between the past event or action and the speaker's present. "Edison has invented the light bulb" conveys the idea that the speaker expects the stated fact to be news to the listener, as it was news to him, or that the statement has some other bearing upon "the present day", broadly conceived. Consider an imaginary conversation in 1879:

Dad, will we be able to read at night without kerosene lamps, gas lamps, or candles in the future?
--Yes, we will, because Edison has invented the light bulb.

In other words: Edison's invention is one you must bear in mind, son, when theorizing about future night-time reading.

If we use a specific time expression that excludes the present, either by confining the action to the past or confining it to the future, then the present perfect will express an idea that does not jibe with that time reference.

I have seen him yesterday. not OK
I have seen him tomorrow. not OK
I have seen him on March 3rd, 2015. not OK
I have seen him as recently as March 3rd, 2015. OK
I have seen him now and then. OK
I have seen him often. OK
I have seen him rarely. OK
I have seen him today. OK, because it means "earlier today" but saw is also possible

Note the "ever" and the indefinite article "a" in the song lyric:

I wanna know, have you ever seen the rain
Comin' down on a sunny day?

Those time references "ever" and "a sunny day" are general, not specific. Ever means "at any time" and today could be a sunny day. These references do not exclude the present.

P.S. On the Korean War example in the OP.

The Korean War has broken out in 1950. not OK

Let's say a newscaster is reporting the news that the war has begun:

War has broken out on the Korean peninsula.

War has broken out in the past twenty-four hours on the Korean peninsula.

War has broken out in the last few days on the Korean peninsula.

Now let's say that the armistice is being signed.

The war in Korea has ended.

Now let's say soldiers up in the mountains, cut off from communications, are still holed up a week after the armistice. A platoon arrives on the scene and informs them that the war is now over.

The war has ended.

"When?" they ask.

The war ended a week ago.

The war's end has bearing upon these soldiers now, to be sure. That idea is expressed in the first sentence even though it lacks any time reference but the tense. In the second sentence, however, we are no longer talking about the war's relevance to the present. The time reference a week ago expressly excludes the present. It speaks of the end of the war itself, not about the end of the war as it relates to the mistaken perception of those soldiers, namely that it was still going on.

  • I judge the following grammatical: Have you seen John recently? Yes, as a matter of fact, I've seen him yesterday. Others may prefer I've seen him just yesterday. – GoDucks Jan 6 '16 at 15:55
  • @GoDucks But why not just use I saw him yesterday? The present perfect focus on present so the time expression yesterday makes a contradiction. – Alejandro Jan 6 '16 at 16:59
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    @GoDucks: All "ears" are not alike. IMO, the speaker in your hypothetical may be understanding "just yesterday" as synonymous with "recently" in the question posed. But to my ear, "I saw him just yesterday" would be grammatical, and "I've seen him just yesterday" is kissin' cousins with "I seen him just yesterday." – Tᴚoɯɐuo Jan 6 '16 at 18:35
  • Yes, the speaker considers yesterday to be part of recently, which is why it works. And I would view that as standard not non-standard like I seen....also @Subjunctive – GoDucks Jan 6 '16 at 22:13
  • An alternative parsing: "Why, yes, I have seen him — just yesterday, in fact." That is, there's ellipsis of "it was". I'd have to hear how you said it, to be sure. – Tᴚoɯɐuo Jan 7 '16 at 11:01

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