We ________ the difficulty together, but why didn’t you tell me?

——Can I walk across the road now, mum?——No, you_______. You have to wait until the light turns green.

—Is Nick coming by train?—He should, but he ________ not. He likes driving his car.

If you don't know the word, you can _____ in the dictionary. 

It ______ be the postman at the door. It’s only six o’clock.