1. (2016·哈尔滨) Nowadays, we don't have enough resources to use. So it's everyone's duly to save them for the future. To save resources， we should __________.

①throw away a pencil without completely using it

②collect waste things for recycling

③go to school by kike instead of by car

④turn off the tap while brushing our teeth

⑤keep the lights on day and night