I don't think I'll be able to go to the United States anymore.
I don't think I can go to America again.
ーI don't think I'll be able to go to the United States anymore.
「もうアメリカには行けないと思う」
I don't think I'll be able to ... anymore. で「私はもう…できないと思う」
ーI don't think I can go to America again.
「もうアメリカには行けないと思う」
I don't think I can go to ... again. で「私はもう…に行けないと思う」
ご参考まで!