Answer:
1) That cut looks infected, you should go to the doctor.
2) I couldn't eat my dinner last night, my stomach hurt.
3) Glen may come with us to the movies if he finishes his work.
4) I would like to learn English some day.
5) We would have to break the window because we locked the keys inside the car.
Note that these answers can be different and I tried to make it so that they make the most sense in the context.