题目内容
（请给出正确答案）
[主观题]
Nous （connaître) ce garçon, il y a trois ans.
提问人：网友niujunli
发布时间：2022-01-07
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Filtration 1. Coccagno, Luciano, Filtration: Theoretical Considerations & Practical. Results, Culligan International Company. 2. McPeak, John F. and Harold L. Aronovitch, Iron in Water and Processes for Its Removal, Hungerford and Terry Inc. , Clayton, N.J. , 1983. 3. Guidelines for Canadian Drinking Water Quality, 4th ed., Minister of National Health and Welfare, Ottawa, 1989. 4. Nalco Water Treatment Handbook, 2nd ed., edited by Frank N. Kemmer, McGraw-Hill Inc., New York, 1988.
Softening 1. Owens, Dean L. , Practical Principles of Ion Exchange Water Treatment, Tall Oaks Publishing, Inc., Voorhees NJ, 1985. 2. Sybron Chemicals Inc., A Look at the Synthesis of Ion-Exchange Resins, McGraw-Hill Publishing Co. inc., New York,1963.
High Purity 1. Meltzer, Theodore H., High Purity Water Preparation, Tall Oaks Publishing, Inc., Littleton, CO, 1993.
These references most probably appear ______.
A．below an article on water purification
B．below an article on health and medicare
C．in a do-it-yourself book
D．in an operation manual
