以下几题都是SAT考试中出现的错误比较多的题目，请认真做题，并找出你错误的原因是什么原因，是题目没有读懂，还是基本数学知识存在缺陷，还是自己粗心大意？

　　1.The first three numbers of a sequence are 1, 3, and 5, respectively. Every number in the sequence beyond the first three numbers can be found by taking the three preceding numbers, subtracting the second from the first, and adding the third. Which of the following is the sum of the first 40 numbers of the above sequence? 【sequence数列, subtract减】