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Beat me to it, except I don't see the ambiguity, the primary definition of night is the period from sunset to sunrise. 

Secondary definitions reference evening and the period between afternoon and bedtime and involve a social aspect which would not be a concern for astronomical viewing.

Regards,

Bob II

Re: Quiz about the Southern Cross
From: Frank Reed
Date: 2017 Sep 24, 09:10 -0700

The original question was:
"Are there areas on Earth where the Southern Cross can be seen with naked eyes and even during a short period in any night in the year ?"

There's a wee, little ambiguity here. If I go to the South Pole, I can see the Southern Cross all night long --night just happens to last five months (after subtracting out a few weeks of twilight at each end). Point being, you didn't really mean "any night" but presumably "any 24-hour period", right? :)

By the way, for those of us in the northern hemisphere, if you want to imagine something similar, Cassiopeia is about the same size and sits near 60°N declination, opposite the approximate 60°S for Crux. Both are about an hour of RA away from 0^h right ascension, so they're not opposite each other (opposite dec; nearly the same RA, which is equivalent to SHA).

Frank Reed