世界水日，我国的宣传主题是“严格管理水资源，推进水利新跨越”，水资源的保护和合理使用已受封人们的普遍关注。下列用水行为符合这一主题的是   （  ）
①将工业冷却水进行循环利用  ②用未经处理的工业污水灌溉农田 ③用洗菜、淘米的水浇花、冲厕所 ④用喷淋节水龙头代替用水较多的旧式龙头  ⑤用大量的水冲洗汽车代替人工擦洗

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    Coffee has become the most popular American drink. Today people in the United States drink more coffee than（比）people in any of the other countries. People drink coffee at breakfast, at lunch, at dinner, and between meals. They drink hot coffee or coffee with ice in it. They drink it at work and at home. They eat coffee ice-cream and coffee candy（糖果）. Coffee is black and very strong. Different people like to drink it in different ways. Some people like coffee with cream or sugar in it. Other people like coffee with both cream and sugar in it. In all ways it is served（提供服务）. Coffee has become an international（国际的）drink.

已知函数f（x）=$\left\{\begin{array}{c}\left|x+1\right|,x\le 0\\ \left|{\log }_{2}x\right|,x>0\end{array}\right.$，若方程f（x）=a（a∈R）有四个不同的解x₁，x₂，x₃，x₄，且x₁＜x₂＜x₃＜x₄，则（x₁+x₂）x₄的取值范围是____ 

5月17日是世界电信日，各大电信公司通过3G网络为客户提供无线视频通话、无线上网等多面服务，这些服务是利用____来传递信息的，它在真空中传播的速度约为____ m/s；当波速一定的条件下，频率越高，波长越____（填“长”“短”）．