During the day, you spend a lot of time running, jumping, laughing, eating, and talking. You use up a lot of energy(能量) , and by the end of the day you’re tired. Sleep gives your body a chance to rest.
But your brain (大脑)and body are not completely at rest during sleep. While you sleep, your mind may think of the things that happened during the day. It keeps the important things in mind as memories(记忆). It also thinks about things you were worrying about, and you may wake up with answers to some of your problems.
You also grow while you sleep. The thing called "human growth hormone (荷尔蒙)" in the body helps you grow during sleep. This growth hormone also helps the body to repair itself.
Sleep helps your body to conserve energy too. You use up a lot of energy during your daily activities. But when you sleep, your body temperature falls, and your "metabolism" (新陈代谢) slows down. You are still using some energy, but much less than when you are awake and active.
Have you ever stayed up past your bedtime? Did you have difficulty getting up the next morning? Maybe you had problems seeing clearly or you cannot think clearly. That was your body’s way of saying, "I need sleep！" A lack ( 缺乏) of sleep can stop your body and mind from working correctly.
【小题1】What does "human growth hormone" do while people sleep?

After my husband died, my world crashed around me. My six children were 10, nine, eight, six, three and 18 months, and I was overwhelmed with the responsibilities of earning a living, caring for the children and simply keeping my head above water.
I was fortunate to find a wonderful housekeeper to care for the children during the week, but from Friday nights to Monday mornings, the children and I were alone, and frankly I was uneasy. Every unusual noise or any late-night phone call filled me with fear. I felt incredibly alone.
One Friday evening I came home from work to find a big beautiful German shepherd(牧羊犬) on our doorstep. It was obvious he wanted to make the house his home. The children took an instant liking to "German" and begged me to let him in. I agreed to let him sleep in the basement until the next day. That night I slept peacefully for the first time in many weeks.
The following morning we made phone calls and checked lost-and-found ads for German’s owner, but with no results. Saturday night he was still with us. 
On Sunday I had planned to take the children on a picnic. Since I thought it best to leave German behind in case his owner came by, we drove off without him. When we stopped to get gas at a local station, we were amazed to see German racing to the gas station after us. He stayed again Sunday night.  
Monday morning I let him out for a run while the children got ready for school. He didn’t come back. We thought we’d never see him again. On Friday evening, German was back again. We took him in, and again he stayed until Monday morning, when our housekeeper arrived. It went like this for almost 10 months. We looked forward to his coming each Monday morning he left home.
Each week, between German's visits, I grew a little braver, but every weekend I enjoyed his company. Then one Monday morning we patted his head and let him out for what turned out to be the last time. He never came back. 
【小题1】What does the underlined part in the first paragraph mean?

Have you ever heard of a famous charity called Operation Smile? We hope we can help you understand how we are trying to help children all over the world.

Operation Smile was started by a doctor and his wife. In 1982, together with some volunteers, they went to Philippines to help children who had holes in their lips or inside their mouths. It was very difficult for them to eat and drink. These volunteers worked very hard. But they worried that they could not carry on with the work because they were short of money. Then they decided to start a charity so that they could help these needy children. They called it Operation Smile.
Operation Smile works in more than twenty developing countries and has cured over 10,000 children who have problems with their mouths. Operation Smile has won many prizes for its work and in 1999 they even started a special event called“The World Journey of Hope”. 5,000 children in 18 countries are cured during the event.
On the other hand, Operation Smile trains local doctors and nurses in developing countries so that they can continue to help children when Operation Smile has left. As to the children with much more serious problems, they will send them to America for further treatment.
So show your kindness and generosity to the needy children now. You can send your donation to Operation Smile at local banks. Many thanks from the children who can smile now will come to you.
【小题1】Operation Smile is a famous _____, which was started by a doctor and his wife.