ever investigation

Your second sentence (I have gone to the US) doesn't automatically imply that you are there now. No, there are no differences between these sentences.

Set, your answer is a surprise to me. How come it doesn't imply the person GONE TO THE US is not there? In what situation would a person not there say this?

Yes.
1. Have you ever visited it?
2. Thanks for calling. Where are you now?

Thank you~

So you agree the person saying I have gone to the US must be in the US? (of course assuming that he is not a liar!)

Yes. The usual question would be "Have you been to the USA?"

"Have you gone to the USA?" is different, but note: "Have you EVER gone to the USA?" means just about the same as the first sentence.

There are subtle differences in the ways they might be used, but I'm tired.

Thank you~

To ask a question of an undegraduate, are they both good and correct English?:

-Has your high school teacher told you the difference between...
-Has your high school teacher ever told you the difference between...

The person being addressed is no longer in high school, so the possibility of being told such things is past; but I am not sure whether the present perfect tense is correct here.

Peter is dead.

Can I say these?:

-Peter has not spoken out against the authoritarian regime.
-Peter has never spoken out against the authoritarian regime.

If Peter is dead, it would be more normal to say, "Peter never spoke out against..."

Peter is dead.

Can I say these?:

-Peter has not spoken out against the authoritarian regime.
-Peter has never spoken out against the authoritarian regime.

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Peter, being dead, is not the determining factor in whether you can use the PP, WB. There are many uses of the PP when the event has finished/been done.

What is important is whether the situation is conducive to a current relevancy/ current importance use. As McTag has noted, in this situation, the tendency is towards the simple past but as he has also noted that doesn't completely rule out the PP.

Context context context!

WB: A distinction usually made:

-I have been to the US. (not there)
-I have gone to the US. (now there)

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Another distinction badly made, I'm afraid, WB. These are called prescriptions and they come from, where else, prescriptivists who have badly analyzed language.

With the right context your second example could indeed mean 'now there' but in a different context it wouldn't be glossed/understood like that .

-///////////////////

WB: 1. Are there any differences between?:

-Have you been to the US?
-Have you gone to the US?

But I feel that there's no difference between

-Have you ever been to the US?
-Have you ever gone to the US?

////://////////

Again, context is of the utmost importance. Prescriptivists forgetting this has been one of the main reasons that these silly prescriptions got started.

Thank you~

But do you not think whether a person is dead affects the tense?

For example, Peter is dead. The possibility of his being able to speak again is past, so only the past tense should be used. But when NEVER is added, it sounds the present perfect is also possible. Of course in this case we assume no one is going to hold a seance to call back Peter's spirit.

Do you agree?

Keep it simple.
I refer you to my previous answer.

WB: But do you not think whether a person is dead affects the tense?


McTag: If Peter is dead, it would be more normal to say, "Peter never spoke out against..."

You can say, "Peter had not spoken out against the authoritarian regime," and also, "Peter had never spoken out against the authoritarian regime."