could - might - should - would

Fill in the blanks with the right modal in the negative form
1. Before taking lessons, he swim. (incapacité)
2. Be careful, what he says be true. (probabilité)
3. If you got up late, you arrive on time. (conditionnel)
4. You be impolite like this. (conseil)
5. They have a serious accident, if they drove slowly. (impossibilité)