Even the dirt on the ground is likely to make climate change worse. Researchers have shown that warmer temperatures are heating the soil, causing microbes     1     (become) more active and release more of the soil's carbon into the atmosphere, contributing to even higher temperatures.

Scientists found a sharp increase in carbon released into the atmosphere by bacteria and fungi in soil from 1990 through 2014. Researchers explain that the carbon comes from     2     the microbes eat, such as the dead plants and leaves. With temperatures     3    (rise), the microbes eat more. And the more they eat, the more carbon they make into carbon dioxide and release into the atmosphere.

Surprisingly, soil lets off about nine times more carbon than human-caused activities, which is in     4     (agree) with what we originally     5     (think). But that is part of a natural cycle: The amount of carbon released into the air is about     6     same as the carbon oceans and plants take in.

    7    , carbon which is released from fossil fuel causes an imbalance. Burning coal, oil and natural gas puts     8     carbon into the atmosphere than nature can take in. The additional carbon heats the air and soil. And     9     the air and soil get hotter, the earth will release yet more carbon that it has been holding.

If something is not done, we are really in trouble, said Rattan Lal of Ohio State University. He held a     10    (believe) that proper soil conservation should be taken into consideration, including avoiding turning the soil, covering off-season crops and leaving crop deposits on the ground.

The total number of tigers in many countries     1     (decrease ) in recent years.     2    the development of Asia, many lands have been divided up for roads, farms, factories, and so on.     3    , tigers are losing their natural habitats. Hunters     4     kill wildlife either for human consumption or for illegal trade have reduced numbers of deer and other animals, making tigers’ food insufficient. Some roads allow people to     5     (easy) get close to places     6     wild tigers live. Tigers     7     (kill) for their fur, bones and other body parts, many of     8    are used as ingredients in medicines. Even though the sale of tiger parts is illegal, some people still take     9    (risk). In 1920, scientists     10     (figure) out that there were 100,000 tigers in the wild. But today the number is in the low thousands.