某温度下有一杯饱和的硝酸钾溶液，欲使其溶质的质量分数改变，下列操作可行的是（　　）

—That's why he can't improve himself.

    Do you love singing, dancing or acting (表演)? Then come to Silver Star Theater School. We have courses (课程) every week in the school holidays for children between 9 and 16 years old.

    If you are 14, 15 or 16, it is only $89 for a week. If you are under 14, it is $95 for a week. You'll find we are cheaper than other schools but much better (更好的)!

    We will give you any clothes you need. But you need to bring your lunch.

    From Monday to Thursday, you will work really hard. Then your family and friends can come and watch you in a show (演出) on Friday afternoon. For many students, this is the best day of the week.

    The first summer course begins on July 21st. If you want to take this course, call Mary before the 12th. The phone number is 884-2901, and you can call between 9 a.m. and 4 p.m. every day.

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