The Development of English Vocabulary

There are about one million English words in all. English is also an international language in this society. You can see English words almost every where, even in non-English-spoken countries.
How does English come into being? Why it has so many vocabularies? In the following passage, I will give you a general picture about these two questions.
The English people are of a mixed blood. The early inhabitants of the island we now call England were Britons, but in fact all the races were the invaders came from Europe. Nobody knows very much about Britain before the Romans came during the first century BC, but there had been at least three invasions before that. The first of these was by a dark-haired Mediterranean race called the Iberians. The other two were by Celtic tribes: one is Gaels, whose descendants are the modern Scots and Irish; another is the Britons, who gave their name to the whole island of Britain. These were the people whom the Romans conquered. The Romans gave the Britons a good deal of their civilization. Then at the beginning of the fifth century Britain was invaded by three tribes from the northern Europe: the Angles, the Saxons, and the Jutes. These three tribes merged into one people, and the three dialects they spoke naturally grew into a single language, the English language.
But at first, the English word made up of only a small part of native words and some borrowed words. The native words were the core words of English. According to a kind of classification of language, English is classified as a Teutonic language, which is a Germanic language. To be more exact, English belongs to the low West Germanic branch of the Indo-European family. Because of the complex history of Briton, the language of English is of a mixed character. On one hand, it shares with West Germanic languages many common words and similar grammatical structures. On the other hand, more than half of the English vocabulary is derived from Latin and French. Besides,...