There are all kinds of trains in the world. There are trains to carry people, trains to carry animals and trains to carry things.

In big cities, the streets are usually very busy. So you can find trains under the ground and trains on a rail above the streets. They carry people in and out of the city.

Can a train run over water? Yes, it can. There are many bridges over the river. The trains can easily run over the water. But it is not easy to build bridges.

Today’s trains have dining rooms for people. You may eat something on the way if you are hungry.

Trains are useful to men, women and children. Many children have model trains. With the model trains they can build their own rails and enjoy the wonderful world of trains.

1.There are _____ kinds of trains in the world.

A a few

B many

C few

D little

解析：选B。B细节理解题。根据“There are all kinds of trains in the world.”可知，世界上有各种各样的火车。故选B。

2.In _____ cities, the streets are usually busy.

A small

B middle

C large

D tiny

解析：选C。C细节理解题。根据“In big cities, the streets are usually very busy.”可知，大城市，街道通常非常繁忙。故选C。

3.The underground trains carry people_____.

A in and out of big cities

B from big cities to small towns

C from small towns to big cities

D in and out of countries

解析：选A。A细节理解题。根据“They carry people in and out of the city.”可知，它们载着人们进出城市。故选A。

4.Many children can enjoy the wonderful world of trains because they _____.

A have real trains

B have model trains

C often take trains

D have real rails

解析：选B。B细节理解题。根据“With the model trains they can build their own rails and enjoy the wonderful world of trains.”可知，通过模型火车，孩子们可以建造自己的铁轨，享受火车的美妙世界。故选B。