Evolution

Life, as it is currently understood, is known to exist only on the planet Earth. The origin of life is still a poorly understood process, but it is thought to have occurred about 3.9 to 3.5 billion years ago on the earth that had a substantially different environment than is found at present. These life forms possessed the basic traits of self-replication and inheritable traits. Once life had appeared, the process of evolution by natural selection resulted in the formation of ever-more diverse life forms. Species that were unable to adapt to the changing environment and competition from other life forms became extinct.

The appearance of photosynthesis in very basic forms of plant life worldwide allowed the sun's energy to create conditions allowing for more complex life. As a result oxygen accumulated in the atmosphere and gave rise to the ozone layer. The incorporation of smaller cells within larger ones resulted in the development of yet more complex cells called eukaryotes. Cells within colonies became increasingly specialized, resulting in true multicellular organisms. With the ozone layer absorbing harmful ultraviolet radiation, life colonized the surface of Earth.

1. Grammar Revision. Find in the text and translate the sentences with:

a) Infinitive

b) Infinitive constructions