1. He must stop his car near the bus station. He mustn't stop his car near the bus station.
2. They must learn all the poems by heart. They mustn't learn all the poems by heart.
3. She must meet us at the railway station. She mustn't meet us at the railway station.
4. I must take the letters from the post office. I mustn't take the letters from the post office.
5. We must overcome all the difficulties. We mustn't overcome all the difficulties.