All living things on the earth need other living things to live on. Nothing lives alone. Most animals must live in a group, and even a plant grows close together with others of the same kind. Sometimes one living thing kills another, one eats and the __①__    is eaten. Each kind of life eats another kind of life in order to live, and together they form a food chains(链子). Some food chains are simple, while others are not. But all food chains begin with the sun, ② and all food chains become broken up if one of the links(连接) disappears.

All life needs sunlight to live on. But only plants can use sunlight directly (直接地). Plants are “factories”. They make food from sunlight, water and things in the soil and air.

Plants feed all other living things. Animals can only use the sun’s energy after it has been changed into food by plants. Some animals feed directly on plants, others eat smaller animals. Meat-eating animals are only eating plants indirectly(间接地).

What about human beings（人类）? We are members of many food chains. We eat wheat, rice, vegetables, fruits and so on. We also eat meat and drink milk. But men often break up the food chains. They kill wild animals and make the rivers, lakes, and seas dirty. When these rivers, lakes and seas are polluted, the fish in them cannot be eaten. If men eat the fish, they will get strange diseases(疾病).

Each form (形式, 方式) of life is linked to all the others. Breaking the links puts all life in danger.

71、在①句的空白处填入适当的词使句意完整、上下文通顺。______________

72、将②句译成中文。                                                  

73、What do plants make food from?

74、在文中找出与下面意思相近的句子并写在下列的横线上。

Human beings often break the balance of nature.

75、找出文中或写出最能表达该短文主题的句子。

仔细阅读下面的短文并按要求完成后面的小题。

     Men have always wondered about the earth they live on and about the ①_____ above them.

       When early men looked at the night sky, they asked themselves a lot of questions. They looked at the moon, and wondered what this strange bright object in the sky was. They did not understand why it changed its shape from night to night. They looked at the stars and planets. They also wondered why some of them changed their positions, while others did not.

       ②他们也思考地球的形状。 Most early people believed the earth was flat.

       ③In different parts of the world, there were different ideas about the universe. The ancient Greeks were the first people to study the universe more scientifically. In the sixth century BC Pythagoras put forward the idea that the world was round. However, he could not explain why people at the bottom of the world did not fall off.

       It was not until the sixteenth and seventeenth centuries that scientists found the answers to some important questions. ④With the help of Galileo’s telescope, people could see the sky more clearly, and find the positions of the stars and planets. Finally in 1665, Isaac Newton explained to the world what gravity (重力) was and people at last understood why they did not fall off the earth.

76.   在文中①处填写一个单词，使得句意完整、上下文通顺。___________________

77. 根据文章内容回答问题。

What questions did early men ask themselves when they looked at the night sky? Write down one of them.

_________________________________________________________________________ 

78. 将文中②句翻译成英语。

       _________________________________________________________________________ 

79. 将文中③句翻译成汉语。

       _________________________________________________________________________ 

80. 写出文中④句的同义句，每空限填一词。

       Galileo’s telescope made ________ __________ for people to see the sky more clearly, and to find the positions of the stars and planets.