If you show you ____ ____ ____ (意识到) cultural differences, most Americans will not worry about answering your questions.

What will the weather be like? Some people say they can know what the weather will be like from birds. When they see birds fly high out to the sea , they know it is a nice day, because birds don't like to fly out when it will rain. When the weather will be bad, the birds come back to the beach. A big wind may come with a rain. Birds do not like to fly in a big wind. They may sit in a tree when rain is coming. Other animals can also tell the weather. It's a cloudy day. The rain is coming. Chickens aren't quiet, and they are running here and there. Frogs(青蛙) are making big noise in the pool. If it is a nice day, the frogs will come out of the water.

在1：500000的地图上，实地距离为20千米的两城市在图上的距离是（　　）