Write the sentence, using 'have (has) been'/'have (has) gone'.
example 0. i haven't seen kate for ages. (she/paris/for a year)
answer 0. she has gone to paris for a year.

1. i have already come home. (i/poland/for a year)

my try is:
1. i have been to poland. i was there for a year.

can we incorporate the period "for a year" into the sentence "i have been to poland."?
is it correct to say, "i have been to poland for a year"? i don't think it is, but i need a confirmation from an expert.
you in advance! i have no more points to give, sorry!

If you want to incorporate 'for a year", you would need to say 'I have been in Poland for a year.'

But as 'been to' suggests just a visit and not a long stay, you may want to use "I had gone to Poland a year ago.'

You could also say: “I was in Poland for a year” (That is more natural English)

from the political point of view it could be said that the candidate   is an effective speaker because she takes a strong position on the issue. it is an open discussion but probably she is making a presentation and can choose which subjects she wants to address. she is very likely to attain her aim which is to convince voters to accept her proposal.