DictationListen to the passage. For question 21—25, fill in the blanks with the

Dictation
Listen to the passage. For question 21—25, fill in the blanks with the exact words or phrases you hear.
   Good morning, everyone. Today, I’m going to talk to you about the history of building and architecture.
   No story is more interesting or impressive than the story of man’s progress through the ages, and in particular the activities of human beings in the art of building. Let’s have a look at this in detail.
   In very early times, around 50,000 years ago, primitive humans lived in trees and caves, where they found protection from wild beasts and shelter from bad weather. However, these natural shelters were pretty uncomfortable and so humans began to think of ways to construct more permanent dwellings, such as tents and huts.
   From these humble beginnings a great variety of architectural style gradually developed, and we see how humans began to master constructional techniques and at the same time to achieve aesthetic desires. In other words, we see how they began to create buildings that were not only functional but beautiful as well.
   Generally, architecture is concerned with the enclosing of space. Another way of saying this is that architecture is about creating a safe, healthy and pleasant space for occupants—that is, a healthy place in which to live and to work.
   There’re three basic principles of architecture and I’d like to run through these now. The first is the principle of function: that is, the purpose of the building in question. The second is the principle of construction: how the building is built or constructed. And the third, after construction, is artistic expression.