根据课文内容填空。
In 1831, Darwin left 32 on the ship, the Beagle. After Darwin had spent some time in 33 , he collected 34 . As he studied these, he noticed that some species of animals were very 35 each other, and he wondered how different species came to exist.
When the Beagle reached the Galápagos Islands in 1835, Darwin noticed that there was 36 the birds’ finches on each of the islands. Darwin suspected that the finches had evolved from 37 and over time, it had slowly evolved into 38 . And that was the answer to how new species of plants and animals came to exist: they 39 .
It was a completely new idea — 40 . Darwin explained this theory in his book, On the Origin of Species. Today, it is regarded as one of the most important works ever written. It has changed 41 forever.