Translation:Could you turn your cell phone off during dinner?
Here 'povus' means 'could', but in another sentence I saw that 'povis' meant 'could' as well. So what is the difference in meaning? In Dutch we use 'zou kunnen' for something that could possibly happen in the (near) future and 'kon' for something that possibly could have happened in the past. Is this also the case with 'povus' and 'povis'?