阅读理解 Many thousands of years ago, people had not learned to build houses or shelters(掩蔽处)of any kind．They lived in caves where they were protected from the rain and snow．The caves were also safe places in which they could sleep without being attacked by bears or wolves． The tools these people used were made of stone, so we call those times the Stone Age．A hard, sharp-edged piece of stone was an axe-head．These people learnt to bind(捆)the stone to a wooden handle using the tough sinews(筋)from legs of animals they had killed．Pieces of flint(燧石)were collected and smashed(粉碎)with heavier rocks to make pointed with sharp edges were used as knives． The people of the Stone Age hunted animals which included deer, wild horses and wild cattle．After eating the meat, they took the animal’s hide, stitched it out on the ground and scraped off the fat．They left hair on the outside．Then, after they had softened the hide by stamping on it, they polished the inside with sandstone．The finished skins gave them rugs and clothes．For needless they poked(戳)thin pointed bones through the skins and stitched them with fine sinews． We are not certain when the Stone Age began．Scientists think it could have been over a million years ago．They do know that it ended in about 3,000 B．C．when people learnt to make things from copper and bronze．There were Stone Age people living in South Africa in the Kalahari Desert, Australia and New Guinea when white settlers arrived not many years ago．In distant parts of New Guinea some tribes have only just begun to use tools made of iron． | 
