（B）

    Traveling is very interesting. Many people love traveling. There are many ways to travel: by plane, by train, by ship or by car. Everyone has their favorite way.

Greg:

    My favorite way of traveling is by car. I can bring my pet dog along. I can travel three hundred miles or only fifty miles a day. I can stop at a good restaurant to enjoy a good meal or at a hotel to spend the night.

Eliza:

    I love traveling by train best! It's very exciting. I traveled most of Europe in 5 months by train. It's the best way to talk with the local people and make new friends on the way. Trains make even the longest trip enjoyable. The train ride to me is just like a big moving party.

    I also like traveling by ship. It is a very great way to spend a vacation. I can go to parties and movies on the ship, and enjoy the blue sky and water.

Danny:

    Planes are my favorite. It's the fastest way of traveling. I can quickly get to another country. Planes have very comfortable seats. I can have something to drink and to eat. I can also read some free magazines and newspapers.

“根深叶茂，树干粗壮”，这是对一棵大树的整体性描述．下图所示的结构层次中，属于器官的是（    ）