"Este segredo deve ficar entre nós."

Translation: This secret must stay between us.

[TiagoMoita_PT]

Any reason why "This secret must REMAIN between us" should be incorrect?

[cloudhorizon]

Looks okay to me, they both have the same meaning in my opinion. Although I guess the one you gave is a little less common compared to duolingo's.

[TiagoMoita_PT]

Agreed. No reason to be marked incorrect though. Thanks.

[ShaneSmith80]

"Remain" is now accepted 8/7/15

[Dr.Fandey]

How about "This secret must stay among us"?

[TiagoMoita_PT]

Hum... for some reason that doesn't sound right to me.

[Dr.Fandey]

Ok! I think, I understood! Thanks a lot, guys!

[Mikenorling]

Why is "This secret needs to stay between us" NOT accepted?