题目内容
H7N9 bird flu is a virus can make people die. We’d better stay away from birds at present.
A. who B. which
C. what D. whom
B 【解析】试题分析：句意：H7N8禽流感是一种能致人死亡的病毒，我们现在最好远离禽类。who 谁，指人；which 引导定语从句，指物；what不引导定语从句；whom引导定语从句时，先行词是人，并且在从句中做宾语。这个定语从句的先行词是a virus，指物，故应选B。
B. 
C. 
The USA is the fourth largest country in the world in size after Russia, Canada and China. The population(人口) of the USA is the third largest in the world.
The Mississippi River is the longest river in America. It's over 6,000 kilometers long. The Mississippi River has been called the "Father of Waters" or "Old Man River". The most important lakes in the United States are the Great Lakes. They are Lake Superior, Lake Michigan, Lake Huron, Lake Erie and Lake Ontario. All of them are between Canada and the United States except(除了) Lake Michigan.
Let us talk about American education(教育). There are two kinds of schools in the United States: public schools and private schools. Most children go to public schools. Their parents do not have to pay for their education. If a child goes to a private school, his parents have to pay for their schooling. Children start school when they are five years old. Most students are eighteen years old when they leave secondary(中级) schools.
根据短文内容，完成表格。
Its size in the world is the fourth largest. | Its 1. in the world is the third largest. | The longest river in America has a length of 2.. |
Of the Great Lakes 3. isn't between Canada and the USA. | The kids in America can have free education in 4.. | Children started school at the age of 5.. |