Human beings are no stranger to extinctions, where entire species     1    . In the last 500 million years, there have been five times when life on Earth has almost ended. According to scientists, we are now entering the Earth's sixth mass extinction, for which human activity will     2    .

There is a long list of reasons why so many species     3    : pollution, deforestation, farming and overfishing. It is clear that human activity has negatively affected all other species on Earth. If a sixth mass extinction occurs, scientists believe that     4     three quarters of all species on Earth could become extinct. In turn, as we humans depend on so many species for our survival, we would also be     5     extinction.

However, it's not too late to     6     now. We need to take steps to set up nature and wildlife reserves, make good use of wind and solar energy, and reduce our carbon footprint.     7    , if we want to survive, we need to stop destroying the planet that we live on and start to protect it.

Species are     1     at an high rate due to human activity. It is clear that human activity     2     all other species on Earth. As we humans depend so much on so many species for our survival, we would also     3     extinction. Thus, we should    4     to improve the situation. For example, we should     5     of endangered animals. Moreover, we should     6     change the way we live. In this way, we might be able to avoid THE SIXTH EXTINCTION.

Firemen had been fighting the forest fire for nearly three weeks before they could get it under control. A short time before, great trees had covered the countryside for miles around. Now, smoke still     1     from the warm ground over the desolate hills. Winter was coming on and the hills threatened the     2     villages with destruction, for heavy rain would not only wash away the soil but would cause serious floods as well. When the fire had at last been put out, the forest authorities     3     several tons of a special type of grass-seed which would grow quickly. The seed was sprayed over the ground in huge     4     by aeroplanes. The planes had been planting seed for nearly a month when it began to rain. By then, however, in many places the grass had already     5    . In place of the great trees which had been growing there for centuries, patches of green had begun to appear in the     6     soil.