题目内容：

词语运用

阅读短文，从方框中选择适当的词并用其正确形式填空，使短文通顺、意思完整。请将答案写在下面题号后的横线上。每空限填一词，每词限用一次。方框中有两个词是多余的。

change , difficult,  that,  plant, little, country ,be, provide, it, what, and , young

Everyone knows lungs are important to people. Do you know what are the lungs of the earth? Forests. The earth can’t breathe without them. It needs 1.   forests to remove carbon dioxide from the air 2.   to make oxygen. In many3.   , such as New Zealand, Canada, and Brazil, forests were cut down to 4.   wood to build houses. Many young volunteers around the world 5.   working in their holidays to plant new trees to replace them.

These young people face many 6.     when they plant new trees. The weather may be hot and dry or it may be cold and wet. There are often many insects 7.     bite these planters on their legs, arms, and faces while they work. They carry heavy bags of small trees, and working in the mountains can be dangerous.

Tree planters are 8.   the world. They plant different types of trees so that birds and animals can live in the forests. Even though tree9.   is difficult, they love their work. They believe that in 50 years their10.   trees will become beautiful forests.