下图为气压带、风带移动规律模式示意图（图中虚线为回归线），关于图中所示季节各纬度带气流运动状况的叙述，正确的是（    ）

阅读下列短文，从每题所给的四个选项中（A、B、C和D），选出最佳选项，并在答题卡上将该项涂黑。

    Teachers at American colleges and universities have many different teaching methods. Some teachers give homework and check the work every day, and students in their classes have to take many exams. Some teachers give only writing tasks. Some teachers always follow a course outline and usually use the textbook, while others send students to the library for tasks.

    The atmosphere in some classrooms is very formal. Students call their teachers Professor Smith, Mrs. Jones and so on. Other classrooms have an informal atmosphere. Students and teachers discuss their ideas together. Teachers dress informally, and students call them by their first names. American teachers are different in their teaching styles.

At most American colleges and universities, libraries and learning centers can be used by students at any time. They can often use tape recorders, video machines and computers. They can buy books, notebooks and other things at campus stores. There are also services to students. They can get advice on their problems from their teachers. Colleges and universities usually offer facilities to students. Some schools have swimming pools and tennis courts. Most have fast food restaurants.

北方冬天的清晨，我们经常看到玻璃窗上有美丽的“冰花”，这是____（选填“室内”或“室外”）空气中的水蒸气遇冷____形成的。