家用炒菜铁锅用水清洗后，放置一会出现红棕色的铁锈，在此变化过程中不会发生的化学变化是（ ）
A．2Fe＋ O2 ＋ 2H2O＝2Fe(OH)2
B．4Fe(OH)2＋O2 ＋2H2O＝4Fe(OH)3
C．O2 ＋ 2H2O ＋ 4e－→ 4OH－
D．Fe → Fe3＋＋3e－
答案：D
之所以出现红棕色的铁锈，是因为铁发生电化学腐蚀，铁作负极失去电子被氧化生成亚铁离子，在电化学中铁不可能直接生成Fe3＋。答案是D。
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| There are about fifteen hundred languages in the world. But 1 a few of them are very 2 . English is one of these. Many, many people use it, not only in England and the USA, but in other parts of the world. About 200, 000, 000 people speak it as their own language, It is difficult to say how many people are learning it as a 3 language. Many millions of people are 4 to do so. Is it easy or difficult to learn English? Different people may have different 5 . Have you ever 6 ads of this kind in the newspapers or magazines? "Learn English in six weeks, or give you 7 back...," "easy and funny…Our records and tapes 8 you master English in a month. 7, Of course, it never 9 quite like this. The  only language that seems easy to learn is the mother tongue. We should 10 that we all learned our own language well when we were 11 . If we could learn English in the same way, it would not seem so difficult. 12 what a small child does. He listens to what people say. He tries what he hears. So it is 13 to say that learning English is easy. We must do a lot of practice. And practice needs great effort and 14 much time. Good teachers, records,  tapes, books, and dictionaries will helpful, 15 they cannot do the students' work for him. | ||||
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