Daming: What are you doing, Lingling?

Lingling:

Daming: What are you writing in your letters?

Lingling:

Daming: When will you leave?

Lingling:

Daming: Will you miss them?

Lingling:

Do you have a bike? Many children like to ride bikes. But where did bikes come from?

The first bike was invented(发明)about 200 years ago. A man in Germany made a thing with two wheels. It was called a bicycle. The wheels were made of wood(由木头制成). The bike was tough to ride. Many people fell off their bikes.

Later, a man made a thing with three wheels. It was called a tricycle. It was easy to ride and safe. But it was very slow.

Since then, bikes have changed in many ways. Today we have many kinds of bikes. People ride bikes everywhere.