People sleep and so do animals（动物也一样）. Every animal sleeps， from the smallest to the largest. March 15 is World Sleep Day（世界睡眠日）. Lets walk into the animal world and find out how the animals sleep.

Brown bats sleep in the day.They sleep upside down（倒挂地）. They can sleep for about 19 to 20 hours under a leaf！ They wake up and fly in the night.

Giraffes need less sleep than other mammals（哺乳动物）. They often sleep for only about 30 minutes a day！ Most giraffes sleep while standing up. And one of their eyes is open and both ears move. In this way， they can protect（保护） themselves from dangers.

Walruses（海象） can sleep and swim at the same time. They can hold their breath（屏住呼吸） for five minutes. Its just enough time for a nap（打盹儿）.

Walruses dont need to sleep every day. They can stay awake（醒着的） for more than three days.

Zebra finches（斑胸草雀） are a kind of Australian（澳大利亚的） songbird（鸣禽）. They can sing while sleeping. They remember a song after hearing it. Then they practice it later in their sleep. Scientists believe sleep helps them to be good singers！

Elephants sleep about 3.5 hours a day. When its time to sleep， elephants go and find a tree. Its safe for them to sleep against a tree. Sometimes they lean（倚靠） on another elephant to sleep.

1. Sharks sleep soundly（熟睡） in the sea. Some divers（潜水者） can touch（触摸） them without waking them.

2. Green tree frogs（树蛙） turn a tan（棕褐色） color when sleeping.

3. Crocodiles（鳄鱼） sometimes sleep with their mouths open.

1. How long do giraffes often sleep a day？

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2. Which country are zebra finches from？

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3. What animals sleep upside down？

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（答案請见P48）