到歐洲入境問題

No... As part of the immgration regulation, you are requested to show you return ticket while you entry any European countries (if you are not a EU passport holder)... And a return ticket means a ticket which have the return date printed on the ticket...
In the case of you not having a fixed return date, you will then have to book a ticket which allow you to change return date... That way you can confirm a date first for your return journey, then to rebook it later... Providing that after your change of date, you actually leave the country within 90days as requested...

根係入唔到啦，歐洲所有國家都會check埋你回程o既機票，因為驚你非法居留。