19． A rainforest is an area（1）
（ cover） by tall trees with the total high rainfall spreading quite equally through the year and the temperature rarely dipping below 16℃．Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate．（2）
the forest cover，these areas would reflect more heat into the atmosphere，（3）
（ warm） the rest of the world.Losing the rainforests may also influence wind and rainfall patterns，potentially causing certain natural disasters all over the world．
In the past hundred years，humans （4）
（begin） destroying rainforests in search of three major resources：land for crops，wood for paper and other products，land for raising farm （5）
（ animal）．This action affects the environment as a whole．（6）
example，a lot of carbon dioxide（二氧化碳）in the air comes from burning the rainforests．People obviously have a need for the resources we gain from cutting trees（7）
we will suffer much more than we will benefit．
Rainforests are often called the world's drug store．More than 25% of the medicines we use today come from plants in rainforests．However，fewer than 1%of rainforest plants have been examined for their （8）
（machine） value．It is extremely likely（9）
our best chance to cure diseases （10）
（lie） somewhere in the world's shrinking rainforests．
