The world of out-of-doors is full of secrets. And they are so interesting that quite a lot of people are busy studying them. All around us are birds, animals, trees and flowers. The facts about how they  1  and grow are as interesting as anything could be. Do you know that one of the greatest presidents of the USA spent hours and hours  2  birds? A businessman who lives near New York city became so  3  in insects that he began to collect them. He now has more than one thousand different kinds carefully  4  in glass boxes. Come then with me, and I will help you find some of nature’s secrets. Let us go  5  through the woods and fields. Here we shall find how a rabbit tells the other rabbits that there is danger. We shall  6  a mother bear and her young ones as they look for  7  and get ready for winter sleep. We shall watch bees dancing in the air to let other bees know  8  they can find food. I will show you many other interesting things, but the thing that I can  9  you is to keep your eyes and ears  10  when you go out of doors. Nature tells her secrets only to people who look and listen carefully.

Animals grow up in different ways. They have lots of lessons to learn.
Some animals are born helpless but their mothers protect them. A newborn kangaroo is the size of a bee. She stays in her mother’s safe pouch. She doesn’t open her eyes for at least five months. A newborn monkey cannot walk. He is carried by his mother. 
Other baby animals can walk soon after they’re born. They learn to run with their mother when danger is near. A baby zebra（斑马）can run an hour after she is born.
Some baby animals are born in a place that is safe. Other baby animals are born in the open. Baby wolves are born in large holes. A baby elephant is born on open, grassy land. Other elephants make a circle（圈）to protect her.  
Animals that drink their mothers’ milk are called mammals. A mother bear’s milk is fatty and rich. Baby bears need lots of fat to keep warm in winter. They have milk for six months. Baby zebras drink milk for six months or more! As baby animals grow they need solid（固体的）food. Baby lions eat what their mother can catch.
【小题1】Which baby animals don’t open their eyes for at least five months?

Animals grow up in different ways. They have lots of lessons to learn.
Some animals are born helpless but their mothers protect them. A newborn kangaroo is the size of a bee. She stays in her mother’s safe pouch. She doesn’t open her eyes for at least five months. A newborn monkey cannot walk. His mother carries him.
Other baby animals can walk soon after they’re born. They learn to run with their mother when danger is near. A baby zebra can run an hour after she is born.
Some baby animals are born in a place that is safe. Other baby animals are born in the open. Baby wolves are born in large holes. A baby elephant is born on open, grassy land. Other elephants make a circle (圈) to protect her.
Animals that drink their mothers’ milk are called mammals. A mother bear’s milk is fatty and rich. Baby bears need lots of fat to keep warm in winter. They have milk for six months. Baby zebras drink milk for six months or more! As baby animals grow, they need solid (固体的) food. Baby lions eat what their mother can catch.
【小题1】The underlined word “mammals” probably means _______ in Chinese.