American English: Been To Vs. Gone To ?

2 and 4 are acceptable and only slightly less common than 1 and 3

The only difference is that you can't use 2 and 4 if you are physically in the place being refered to
So if you asked, 'Have you ever gone to Singapore before?' while actually standing in Singapore, you'd get a funny look from a native speaker of American English.

All are correct and acceptable in American English.
CJ

John: Have you ever gone to Singapore?

Mary: No, I have never _________.

(A) gone (B) gone there

Which choice is correct?

John: Have you ever been to Singapore?

Mary: No, I have never __.

(A) been (B) been there

Which choice is correct?

Both are correct. If you leave out there, it's understood anyway.
(Same answer for both gone and been.)
CJ

If I'm physically in Singapore, can I say "I have come to Singapore many times"?

sitifanIf I'm physically in Singapore, can I say "I have come to Singapore many times"?

Why not?

come to, traveled to, been in, seen, or visited. All of these verbs, and others, are possible. Not gone to -- unless you've forgotten where you are when you say it!

CJ

1. He has been in Singapore for many years.

2. He has been to Singapore for many years.

I think #1 is correct. Is #2 also acceptable?