Here are the answers with the verbs in the correct form:
- If you have a headache, take aspirin.
- If you are tired, take a rest.
- Don't go outside if it is raining.
- Learn English if you plan to study abroad.
- Do more sport if you want to be fit.
- If you feel sleepy, take a nap.
- Open the window if it is hot in the room.
- Turn the TV off if you are not watching it.
- If you feel sad, watch a comedy movie.
- If you do not know what to do, ask Jim.