March 22 is World Water Day. It started in 1993. It not only makes us think about the importance of water, but   also calls on（号召）us to___and protect water. Today, we're facing terrible water problems. Among them, the wastewater problem is rather ___, And the subject of World Water Day in 2017 is “wastewater”.

What is wastewater? It is used water.   Usually, wastewater comes from homes,___, hospital and so on. It is produced by different kinds of activities, including washing machines, taking showers and using kitchens. The rain also___wastewater when it is running down the street during a storm. No matter where it comes from, this kind of water is sure to have____harmful in it．

___must we treat（处理）wastewater? Wastewater has a big influence in our lives. It causes both illness for us and pollution for the environment. We must care for our environment and our own___.

How can we treat wastewater? Different kinds of wastewater need different ways of treatment. Wastewater___homes can be reused. Then there will be___wastewater. Also, factory wastewater has to be cleaned____it goes back to nature.

If you live in Shanghai, you might have taken a “lesson” in sorting (分类) garbage, as the city introduced new garbage-sorting regulations (规章) on July 1, 2019.

As China’s first city to carry out strict regulations on garbage sorting and recycling, Shanghai requires its residents (居民) to sort garbage into four categories (类别), namely, recyclable, harmful, dry and wet waste. If people fail to sort their garbage properly, they can be fined up to 200 yuan.

Since the regulation took effect, the amount of total daily waste in Shanghai has been reduced by an average of 15,500 tons, dropping 26 percent from the end of 2018, while the average daily weight of recyclables hits 4,500 tons, five times higher than the end of 2018, according to the Shanghai Landscaping and City Appearance Administrative Bureau.

The city also rebuilt 21,000 waste sorting stations and more than 40, 000 waste bins have been updated (更新). The city’s waste collection and transportation system (运输系统) is complete, according to the bureau.

“Proper waste sorting protects the environment and saves natural resources,” said Deng Jianping, director of the bureau. “Led by the central government, Shanghai is making efforts to develop long-term solutions to garbage management.”

However, there have also been some problems. Some people complained that it is difficult to deal with wet garbage, as they are asked to remove wet garbage from its bag when dumping (倾倒). According to the sorting rules, the wet garbage must go in the wet waste bin and the bag must go in the dry waste bin.

“This separation is necessary, as it ensures that the wet garbage will decompose (分解) properly and become useful organic (有机的) waste,” the bureau said.

Plastic bags can affect this process. Some people in Shanghai are instead using paper bags that can biodegrade (生物降解) or plastic containers that can be washed and reused, according to Xinhua.