题目

右图是a、b、c三种物质的溶解度曲线，a与c的溶解度曲线相交于P点。据图回答：     ① P点的含义是                                。 ② t2℃时a、b、c三种物质的溶解度由大到小的 排列顺序是                     。 ③ t2℃时将30g a物质加入到50g水中充分溶解，所得溶液是       （填“饱和”或“不饱和”）,溶液质量是      g。 ④ 将t1℃时a、b、c三种物质的饱和溶液分别升温到 t2℃，三种溶液的溶质质量分数大小关 阅读短文，根据所读内容在表格的空格处填上适当的单词或短语，每空不超过3个单词。 　　Happy birthday!Do birthday really make people happy?Of course they do．Birthday celebrate the day when we were born．Besides, that extra candle on the cake suggest another year of growth and maturity(成熟)－or so we hope．We all like to imagine that we are getting wiser and not just older．Most of us enjoy seeing the wonder of growth in others, as well．For instance, seeing our children develop and learn new things makes us feel proud．For Americans, like people in most cultures, growing up is a wonderful process．But growing old?That is a different story． 　　Growing old is not exactly for people in youth-oriented(以年轻人为中心)American culture．Most Americans like to look young, act young and feel young．As the old saying goes,“You’re young as you feel．”Older people joke about how many years young they are, rather than how many years old．People in some countries value the aged as a source of experience and wisdom．But Americans seem to favor those that are young, or at least“young at heart”． 　　Many older Americans find the“golden years”to be anything but golden．Economically,“senior citizens”often struggle just to get by．Retirement at the age of 65 brings a sharp decrease in personal income．Social security benefits usually cannot make up the difference．Older people may suffer from poor nutrition, medical care, and housing．Some even experience age discrimination(歧视)．American sociologist Pat Moore once dressed up like an older person and wandered city streets．She was often treated rudely--even cheated and robbed．However, dressed as a young person, she received much more respect． 　　Unfortunately, the elderly population in America is increasing fast．Why?People are living longer．Fewer babies are being born．And middle-aged“baby boomers”are rapidly entering the group of the elderly．America may soon be a place where wrinkles(皱纹)are“in”．Marketing experts are ready noticing this growing group of consumer．