3 It is therefore not reasonable to expect one device to be effective and efficient for all pollutants.
4 In addition,the types of chemicals in emissions often will dictate the use of some devices.
5 For example,a gas containing a high concentration of SO3 could be cleaned by water sprays ,but the resulting sulfuric acid might present serious corrosion problems .
谢谢
參考答案:1因此希望一种方案对所有污染都有效是不明智的。
2此外，再放射物中的几种化学物质也常常限制住几种方案的实施。
3例如含高浓度SO3的气体能够被水雾所净化，但产生的硫酸可能会导致严重的腐蚀。