题目

某班级从文化用品市场购买签字笔和圆珠笔共15支，所付金额大于26元，但小于27元，已知签字笔每支2元，圆珠笔每支1.5元，则其中签字笔购买了________支． 答案：8 【解析】设签字笔购买了x支，则圆珠笔购买了（15－x）支，根据题意列不等式组解这个不等式组得7＜x＜9．因为x为整数，所以x＝8． 【难度】一般Study BooksBasic Study Manual Hardcover (精装书)：$ 37Future success depends on the ability to learn. Here are the answers to the questions most often asked by parents, teachers, business trainers and by students themselves. Read this book and learn:What the three barriers (障碍) to study are and what to do about them.What to do if you get tired of a subject you are studying.Twenty-six simple drills to help you learn how to study easily, rapidly and with full understanding.Buy and read Basic Study Manual and use it do dramatically improve your ability to study.Study Skills for Life Hardcover: $32L. Ron Hubbard’s study technology for children opens the door to their future success by giving them the ability to study and learn. Fully illustrated (说明，阐明) for easy comprehension.Learning How to Learn Hardcover: $25The basics of effective study for 8 to 12-year-olds, fully illustrated. Children who read and apply the materials in this book regain their liking for study and their ability to apply this knowledge in life. Get this book for a child you want to see win at his studies!How to Use a Dictionary Picture Book for Children Hardcover: $36In spite of billions of dollars spent on “educational research”, children are not taught the most basic skills of learning, even the most basic of these: how to use a dictionary. In fact, a research of educational books for children found no book that told them how to use a dictionary or that one should. Written for children 8 to 12-year-olds, this fully illustrated book will teach your child:How to find words in a dictionary.The different ways that words are used.What the different marks and symbols that are used in a dictionary mean.How to use a dictionary to correctly pronounce words.It includes a section for parents and teachers showing you how to use this book with children. Buy this book and give it to your children to unlock their education. What’s more, you will just pay 50% for it before May 1, 2014.The purpose of the passage is to _______.A. show readers how to use the four booksB. help children to learn EnglishC. enrich students knowledge about natureD. sell the four books to students.