A、The dangerous twists and turns along the course. B、The changeable weather in a single day in North Germany. C、The preparation

Germany’s Rhine River is hundreds of miles long, but not all of it is the "Romantic Rhine" of guidebooks. The stretch of river where you can see castles, villages, and vineyards, runs 36 miles from Koblenz in the north to Bingen in the south. Visitors like coming to this part of Germany because the scenery is actually stunning. Whether you travel by car, train, or boat, you’ll see high hills stretching away from the river, topped with castles and vineyards. Some of the castles are open for touring during the tourist season, while others are hotels, hostels, or the homes of some organizations.
    The best time to visit the Rhine is during the summer, when you can take full advantage of the sights. Traveling in a cruise yacht is more fun when you can sit in the open rather than down below. Of course, be prepared for tourist crowds during the summer.
    There are several ways to travel along the Rhine. Several river cruise companies offer tours. It takes about two hours to cruise from St. Goar to Bacharach, and most visitors agree this is the most scenic part of the Rhine River. You can also take the train that runs between the villages in the area, and stop anywhere along the way. Another option is to drive the highway that’s on the banks of the river, or ride a bicycle along a trail. If cyclists or drivers want to get to the other side of the river, a number of ferries are available to get them across.
22. Why do people like to visit Germany’s Rhine River according to the speaker?
23. What does the speaker say about the castles?
24. What does the speaker remind summer visitors of?
25. How can cyclists or drivers get across the Rhine River?