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聚合硫酸铁(PFS)是水处理中重要的絮凝剂,如图是以回收废铁屑为原料制备PFS的一种工艺流程.

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根据短文内容和首字母提示,填写所缺单词。
       The development of the English language took a giant step in 1607. Three small British ships c____  the Atlantic Ocean. They began to call areas of their new land by words borrowed from the native people. For example, many of the great r____ in the United States are taken from American Indian words. The Mississippi, the Tennessee, the Missouri are examples. This borrowing or adding of foreign words to English was a w____ of expanding(扩大)the language. The names of three days of the week are good examples of this. The people from Northern Europe honored three gods with a special day each week. The gods were Odin, Thor and Freya. Odin's-day became Wednesday in English, Thor's-day became T____  and Freya's-day became Friday.
     Experts cannot explain many English words. For h____  of years, a dog was called a “hound.” The word is still u____  but not as commonly as the word “dog.” English speakers just started using it. Other words whose origins are unknown i____ “fun,” “bad,” and “big.”
    English speakers also continue to invent n____  words by linking old words together. A good example is the words “motor” and “hotel.” Many years ago s____  linked them together into the word “motel.” A motel is a small hotel near a road where people travelling in cars can stay for the night.
    Other words come from the f____  letters of names of groups or devices. For example, the North Atlantic Treaty Organization is usually called NATO.