as

[Cosmos]

Hello, teacher!

Can I use 'as' here?
- It still remains (as) a problem.

Thank you very much.

[Alan]

Yes, but the sense would be very slightly different: It still remains a problem means simply that 'it is still a problem', while It still remains AS a problem means that 'it still remains and it is a problem', placing emphasis on the fact of its remaining rather than on that of its continued 'status' as a problem!