下列关于脱氮的说法错误的有( )。
A．折点氯化过程是在二级出水中投加氯，直到残余的全部溶解性的氯达到最低点(折点)，使水中氨氮全部氧化
B．在传统的处理过程中，无机氮含量经一级处理后，其含量增加50%左右，不受二级(生物)处理的影响
C．控制氮含量的方法主要有生物硝化—反硝化、折点氯化、选择性离子交换、氨的汽提，不管采用哪种方法，氮的去除率都可超过95%
D．在生物硝化—反硝化中，无机氮先通过延时曝气氧化成硝酸盐，再经过厌氧环境反硝化转化成氮气，从而去除污水中的氮
参考答案：B,C
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| A good dictionary is 1 important tool (工具). It will tell you 2 only what a word means but 3 how it 4 . A dictionary needs to be printed again about every ten years. Languages develop (发展) and a good dictionary must 5 these new changes. A new English dictionary will only tell you 6 most people use the language today. It will not tell you what is right 7 wrong. It may tell you the right time to use a word. If only 8 people use a word, a dictionary will 9 tell you this or not list (编列) it. 10 dictionary will tell you many interesting facts. If you type (用打字机打) a word and the word is too long, 11 in your dictionary. All dictionaries show you 12 to break (拆开) a word. And they also show you how a word 13 . Every dictionary, of course, tells you what a word means. But some words, like "get" or "take", may have lots of meanings (意思). In some dictionaries, the main (主要的) meanings are often listed first. In 14 , the newest meanings are listed last. So before you use your dictionary, you should always 15 the front part. This part explains 16 . Some dictionaries also show you where a word comes 17 . Do you know that the word "brand" (标记) comes from an old word? This old word means "to burn". This is because 18 years ago people burned their names on tables or boats to show who 19 them. They also burned their own names on their farm animals 20 they would not be stolen. Your dictionary also has a lot of other interesting facts in it. After you have learned to use a dictionary, it can become your best useful book. |
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