题干

海水淡化可采用膜分离技术,如图所示,对淡化膜右侧的海水加压,水分子可以透过淡化膜进入左侧淡化池,而海水中的各种离子不能通过淡化膜,从而得到淡水.对加压后右侧海水成分变化进行分析,正确的是(   )

A:溶质的质量增加

B:溶剂的质量减少

C:溶液的质量不变

D:以上三种情况都有可能

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B

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    National Rankings: Best High Schools

    The U.S. News rankings include data on more than 22,000 public high schools in 50 states and the District of Columbia. Schools were awarded gold, silver or bronze medals based on their performance on state assessments and how well they prepare students for college.

    About the Awards

    Gold—Top 500 Schools based on highest college readiness.

    Silver—High-performing schools based on lower college readiness.

    Bronze—High-performing schools based on state exam performance,  listed alphabetically.

    Award Distribution

    Gold 2.4%

    Silver 10.3%

    Bronze 16.8%

    No Medal 70.5%

    HOW We Determine the Awards

    STEP 1 Students perform better than expected in their state.

    We looked at reading and math results for students on each state's proficiency(水平) tests and then factored in the percentage of economically disadvantaged students, who tend to score lower.

    STEP 2 Disadvantaged students perform better than state average.

    We compared each school's math and reading proficiency rates for disadvantaged students--black, Hispanic and low-income—with the state wide results for these student groups and then selected schools that were performing better than their state averages.

    STEP 3 Student graduation rates meet or are greater than a national standard.

    We left out schools from consideration if their graduation rates were lower than 75 percent--a starting point that is higher than a federal law that requires states to give extra resources to schools below 67 percent.

    STEP 4 Students are prepared for college-level coursework.

    We calculated a College Readiness Index,which is based or the school's AP participation rate and how well the students did on those tests. Tiebeakers were used to determine ranks of schools that achieved the same College Readiness Index.