12. A marathon is usually a big public event. In the city where the marathon is held hundreds of people give their time and effort to make the race possible. The city police block traffic on the main roads. Some runners thank the officers as they run by. Every few kilometers there are volunteers who offer water to the runners. Lots of people cheer.

Summary of Section 12:

Marathons are significant public events that rely on the support of many people. City police manage traffic on main roads to facilitate the race. Runners often express gratitude to the police officers they pass. Volunteers are stationed every few kilometers to provide water to the participants, and spectators contribute to the lively atmosphere by cheering.