Why is Belarusian opposition participating in parliamentary election?

Почему белорусская оппозиция участвует в парламентских выборах и какой результат

The opposition’s goal has been disused in the joint project of ePramova and Euroradio. Head of the election headquarters of the campaign Tell the Truth Syarhei Vaznyak, ex-presidential candidate, leader of the unregistered Belarusian Social-Democratic Party ‘People’s Hramada’ and senior deputy of the Movement For Freedom Mikalai Statkevich and representatives of Yuras Hubarevich’s right-of-centre coalition took part in the discussion. Journalist Paulyuk Bykouski was the moderator.

Most opponents to the regime agree that it is necessary to participate in the election campaign. However, all of them are saying that there are no elections in Belarus and that the votes are not calculated fairly. Why are they taking part in the election?