Pool experts have determinded the proper levels of chemicals
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Pool experts have determinded the proper levels of chemicals that must-------in pool water to protect the swimmers from infection and the equipment-------corrosion and damage.Chlorine keills harmful organisms,but it won't work properly if the alkalinty of the water is too----.If the calcium content of the water is inadequate,the water will leach calcium from the walls of the pool,------them
1.A.maintain B.be maintained C.have maintained D.be maintaning
2.A.by B,from C.for D.of
3.A.low B.below C.under D.beneath
4.A.have weakened B.is weakening C.weakening D.weakens
1.A.maintain B.be maintained C.have maintained D.be maintaning
2.A.by B,from C.for D.of
3.A.low B.below C.under D.beneath
4.A.have weakened B.is weakening C.weakening D.weakens
1.选B.这里是一般的情况.maitain维持,保持.游泳池中的学药品的含量必须保持在一个恰当的水平.在这里要用被动语态,是人类保持其含量.
2.选B.and the equipment-------corrosion and damage与前一短语to protect the swimmers from infection 结构是一样的,只不过是省略了一些相同的词而已.
3.选A.如果水中碱的浓度太低,它就不起作用了.
4.选C.表示伴随动作.
2.选B.and the equipment-------corrosion and damage与前一短语to protect the swimmers from infection 结构是一样的,只不过是省略了一些相同的词而已.
3.选A.如果水中碱的浓度太低,它就不起作用了.
4.选C.表示伴随动作.
Pool experts have determinded the proper levels of chemicals
Experts have been warning ---of the risks caused by passive
翻译:we know that the levels of carbon dioxide have increased
Sea levels have been rising ____ the beginning of this centu
Experts have been warning ---of the helth risks caused by pa
Experts have been warning of the health risks caused by pass
英语翻译82、Experts have been warning for some time of the health
the trigger chemicals中of+the+名词的用法!
pool deck Some of the best views of any city I have seen hav
英语翻译The 'List of Approved Chemicals with Corresponding Brand
people are concerned that the persistence of high levels of
we swim in the ___(swim)pool.we have a lot of things___(pack