二、语法填空（共10小题，每小题1分，满分10分）
阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空.
Rivers are one of our most important natural resources. Many of the world’s great cities are located on rivers, and almost every country has at least one river 16 (run) through it . The river plays 17 important part in the lives of its people.
Since the beginning of history, people 18 （use） rivers for transportation. Among all the rivers in the United States, the 19 (long) one is the Mississippi, and the lifeline of Egypt is the Nile. 20 transportation, rivers give water to drink, water for crops, and chances for fun and recreation for the people 21 live along their banks.
However, large cities and industries that are located on rivers often make problems. As the cities grow 22 size and industries increase in number, the water in the rivers becomes 23 （pollute） with chemicals and other materials. People will learn the 24 （important） of doing more to keep their rivers clean 25 they want to enjoy the benefits of this natural resource.
