"nuqDaq 'oH juHlIj'e'."

Translation: Where is your home?

[Vortarulo]

There should be a question mark after the Klingon sentence.

[Vortarulo]

For some reason I cannot see the Klingon flag (should be level 5) after my other flags. This is weird.

[jdmcowan]

I don't think we can change it at this point.

[mizinamo]

loghaD and I can still remove sentences and add new ones.

(At least I can; I assume loghaD can too, as he's also a golden contributor.)

[mizinamo]

True.

I've removed this sentence and replaced it by one with a question mark.

[JamesTWils]

I'm still seeing one with a period.

[mizinamo]

On general strengthening, or on learning/repeating one particular unit?

From other courses, I've heard reports of "zombie" sentences that were supposedly deleted show up occasionally under circumstances that are not clear to me, but "general strengthening" often seems to be the "culprit".

I'm afraid there's nothing I can do about that -- I'd say it's a bug in Duolingo.

You could try logging out of Duolingo and closing your browser, in case it's got something to do with caching, but I'm not sure whether that would help. (Or if you are using an app, waiting for the next version of the app to be released.)

[JamesTWils]

For me, it was in my first run of the unit on Windows.

[Michael.Lubetsky]

As am I.