题目内容
Aluminum is lightweight, rustproof and easily shaped into different forms. By mixing it with other metals, scientist have been able to produce a variety of alloys, some of which have the strength of steel but weigh only one third as much.
Today, the uses of aluminum are innumerable. Perhaps its most important use is in transportation. Aluminum is found in the engines of automobiles, in the hulls of boats. It is also used in many parts of airplanes. In fact, the huge "airbus" planes would probably never have been produced if aluminum did not exist. By making vehicles lighter in weight aluminum has greatly reduced the amount of fuel needed to move them. Aluminum is also being used extensively in the building industry in some countries.
Since aluminum is such a versatile(多用的) metal, it is fortunate that bauxite(铝土矿) , which is one of its chief sources, is also one of the earth's most plentiful substances. As the source of aluminum is almost inexhaustible, we can expect that more and more uses will be found for this versatile metal.
The price of aluminum was sharply reduced when people discovered a new refining process with the aid of______.
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We can separate the mixture into the pure chemical compounds______it is composed.
The idea of a special day to honor mothers was first put forward in America in 1907. Two years later a woman, Mrs. John Bruce Dodd, in the state of Washington proposed a similar day to honor the head of the family—the father. Her mother died when she was very young, and her father brought her up. She loved her father very much.
In response to Mrs. Dodd's idea that same year—1909, the state governor of Washington proclaimed (宣布) the third Sunday in June is Father's Day. The idea was officially approved by President Woodrow Wilson in 1916. In 1924, President Calvin Coolidge recommended national observance of the occasion " to establish more intimate (亲密的) relations between fathers and their children, and to impress upon fathers the full measure of their obligations. " The red or white rose is recognized as the official Father's Day flower.
Father's day took longer to establish on a national scale than Mother's Day, but as the idea gained popularity, tradesmen and manufacturers began to see the commercial possibilities. They encouraged sons and daughters to honor their fathers with small thank-you presents, such as a tie or a pair of socks, as well as by sending greeting cards.
During the Second World War, American servicemen stationed in Britain began to request Father's Day greeting cards to send home. This generated a response with British card publishers. Though at first the British public was slow to accept this rather artificial day, it's now well celebrated in Britain on the third Sunday in June in much the same way as in America.
Father's Day seems to be much less important an occasion than the Mother's Day. Not many of the children offer their fathers some presents. But the American fathers still think they are much better fated than the fathers of many other countries, who have not even a day for their sake in name only.
When did Father's Day officially begin to have national popularity？
封闭式基金交易的竞价原则和买卖程序与买卖股票、债券一样。()
证券公司应当将集合资产管理计划设定为均等份额。()
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