----- It was a red light, William. You ________ the car.------- Sorry, I didn’t see it.

 When I lived with my roommates in the university, we ________ often talk into the night.

If you have difficulty_______a decision，wearing red_______it easier for you to take action．

– Who didn’t turn off the light after school yesterday?– It ______ be Lucy. She told me she was the last one to leave the classroom.

We can hardly believe such a young boy ______ travel around the world all by himself.