1. He (can`t/may not) walk so quickly cause his leg is still aching.2.There was not a single cloud in the sky, and we ( might/were able to) see the stars. 3.He (need/may) arrive on the next train.4. He( may/has to) light a fire,it is becoming too dark. 5.He (is to/can) return to Paris tomorrow in order not to be late.