题目内容
.带传动计算是根据计算功率和小带轮转速确定带的型号；确定最小带轮致敬，以限制弯曲应力；中心距不可过小，否则单位时间内应力变化次数增加，加速疲劳损坏且使包角过小；也不宜过大避免产生颤动。一般情况下包角（ ）120°，同时要保证适宜的张紧力及适当的皮带根数。
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Many deaths from home fires are the result of burns and panic, but most are caused by deadly smoke and gases. These fatal fires are often caused by such careless acts as throwing away a lighted match or cigarette, allowing rubbish to pile up, overloading electrical wires, or misuse of heating and cooking equipment.Few families go to bed at night without first checking to make sure that the doors and windows are locked, but they overlook a very basic fire safety rule. This rule states that people should sleep with their bedroom doors closed. Nighttime fires are most serious because the family is asleep and the discovery of fire is usually too late.A closed bedroom door gives extra protection by delaying the gases and fire, thus giving the family a few minutes to escape.At the first sight of fire in a home, it is necessary for everyone to get out of the house, especially children and elderly persons who may need help.Not everyone flees (逃跑) quickly from a burning home. Children often panic and hide in closets or under beds. Being prepared or knowing what to do in case fire breaks out can mean the difference between life and death. All members of the family should know certain basic steps.Everyone should know an escape route and second route from each room in the house. Very young children and old persons should receive careful thought when mapping out (制订) family escape plans. Both groups will need special help in escaping from home fires. A family ’should deter mine a way in which any members can sound an alarm. It is likely that fire may block hallways and prevent a person from reaching other bedrooms. Family members should be taught not to waste time getting dressed or collecting valuable possessions. Speed is necessary in escaping from fire. The most serious fires happen during（）
Auctions (拍卖) are public sales of goods, conducted by an officially approved auctioneer. He asked the crowd to gather in the auction room to bid (出价，喊价) for the various items on sale. He encourages buyers to bid higher figures, and finally names the highest bidder as the buyer of the goods. This is called "knocking down" the goods, for the bidding ends when the auctioneer bangs a small hammer on a raised platform.The ancient Romans probably invented sales by auction, and the English word comes from the Latin "auction", meaning "increase". The Romans usually sold in this way the spoils taken in war; these sales were called "sub hasta", meaning "under the spear (矛)", a spear being stuck in the ground as a signal for a crowd to gather. In England in the eighteenth and nineteenth centuries goods were often sold "by the candle"; a short candle was lit by the auctioneer, and bids could be made while it was burning.Practically all goods can be sold by auction. Among these are coffee, skins, wool, tea, cocoa, furs, fruit, vegetables and wines. Auction sales are also usual for land and property, antique furniture, pictures, rare books, old china and works of art. The auction rooms at Christie’s and Sotheby’s in London and New York are world famous.An auction is usually advertised beforehand with full particulars(细节)of the articles to be sold and where when they can be viewed by the buyers. If the advertisement cannot give full details, catalogues are printed, and each group of goods to be sold together called a "lot", is usually given a number. The auctioneer need not begin with Lot One and continue the numerical order, he may wait until he notices the fact that certain buyers are in the room and then produce the lots they are likely to be interested in. The auctioneer’s services are paid for in the form of a percentage of the price the goods are sold for. The auctioneer therefore has a direct interest in pushing up the bidding. The end of the bidding is called "knocking down" because（）
俄国最早的国立初等学校开办的时间是在（）。
下列条件之一者宜采用立式多工位组合机床的布置形式（ ）。
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