During my second year of nursing school，our teacher gave us a test.I was a hard﹣working student and I did well1all the subjects.I finished the questions 2until I read the last one，"What is the first name of  the woman3cleans the school？"

    Of course this was only a joke.I saw4 cleaning woman every day.She is short and about 60 years old.

    She has dark hair.5 how would I know her name？I have never talked with her before.In fact，I've never even thought about6to her!I stared at my paper.7 guilty I felt! Finally，I handed in my paper，but the last question 8.

    Before the class ended，one student asked the teacher9the last question would count into our grade.

    "Of course，"the teacher said，"In your life，you will meet10 people.It's important for you 11 them.They deserve（值得）your attention and care，even if all you do is just 12 hello."I'll never forget that lesson.Everyone deserves our attention and we13 try to get to know all the people who work and live around us.That was14 lesson of my life.Later that day，I 15that the cleaning woman's name was Dorothy.

下列对露置在空气中已部分变质的氢氧化钠溶液样品进行的相关实验中，实验现象及结论合理的是

﹣4，﹣|﹣ $\frac{4}{3}$  |，0， $\frac{22}{7}$ ， $\frac{\pi }{2}$ ，2013，﹣（+5），+1.88，0.010010001…，﹣2.33…．

整数集合{       }

非负数集合{       }

分数集合{       }

无理数集合{       }．