题目

一个质数的3倍和一个质数的2倍之和等于2000，那么这两个质数之和是多少？ 答案：解：因为2000为偶数，个质数的2倍一定为偶数，则另一个质数的3倍也一定为偶数，偶数×3=偶数，质数中只有最小的质数2为偶数，2×3=6，2000﹣6=1994，1994÷2=997，即另一质数为997，所以，这两个质数为997+2=999．答：这两个质数之和是999． 根据下列每段文章的含义重新排列文章的顺序 A． There was a girl sitting in front of me．Her name is Pat．She is very friendly．We felt like friends already! At the end of the class she said, “It’s nice to meet you, Jenny．We’ll be classmates!” I didn’t feel so nervous any more． B． My first class was math．I really like math．Some people think girls aren’t good at math, but I always get good marks in math．It’s easy for me．I went into the classroom and sat down at the second desk right near the door． C． I left math class and began looking for the science classroom．It was upstairs．I looked and looked, but I couldn’t find the stairs．It would be terrible to be late for my first class．I hurried down the hall and finally saw the stairs．I ran quickly up the stairs．Suddenly I tripped(绊倒)and my binder(活页夹)fell down．Many papers flew all around．I was so embarrassed．Just then, Pat came up the stairs with two friends．She saw me and said, “Hi, Jenny．” Her two friends picked up all the papers and handed them to me．“Thank you,” I said．“No problem, ” they answered． D． Today is my first day of high school．It is the most exciting day of my life．When I walked into the school, I became nervous．It is so big that I was afraid I might get lost．I didn’t know anyone and I felt lonely．