完形填空

　　Every August on the island of Heimaey, off the southern coast of Iceland, young people often take a walk along the streets throughout the night. What's more, their parents allow them to ___1___. Why? The children of Heimaey are going to ___2___ young puffins-small black-and-white seabirds.

　　The cliffs（悬崖）above the town are ___3___ to a large group of puffins. The birds dig holes all around the cliffs. These holes are their homes. Their ___4___ stay in the holes for about seven weeks. Then they begin to leave. Some move slowly on their ___5___ wings and feet down to the northern Atlantic Ocean that surrounds Heimaey. ___6___, they swim, which they can do naturally, and learn to dive for fish. ___7___, however, may lose their way at night and ___8___ themselves in the town instead. On the ground, the young seabirds are ___9___. Because their wings are not fully developed, they cannot ___10___ quickly to sea and safety. The birds then become a good ___11___ for cats and other animals. For many years, islanders have ___12___ the young puffins. Early at night in late August, children ___13___ thick paper boxes and lights hurry to the seashore to catch puffins. They spend most of the night ___14___ after the birds. They put the birds they've caught in ___15___ and take good care of them. The next morning the children take the puffins to the ocean and set them ___16___. The birds will live ___17___ until they are at least two years old. Then they will ___18___ to the cliffs to build homes of their own for their families.

　　___19___ the children of Heimaey always come to save puffins? “Yes,” answer the boys. “We look forward to it. The ___20___ time for us is setting the birds free.”