题目

Many students like learning History. But do you know history class in the USA is d【1】 from that in China?At Chinese middle school, the history textbook is thin. T【2】 are only about 100 pages(页) in it. Before class, the students read the textbooks to get ready for the lesson. In class, they listen to the teacher and take n【3】. After class, they do a lot of exercises. Sometimes they do not need to k【4】 much about the background (背景) of the historical event.B【5】 in the USA, students have a heavy, thick textbook. It has m【6】than 1,000 pages. Before class, students hav如图，是二次函数y=ax2+bx+c图象的一部分，其对称轴为直线x=1，若其与x轴一交点为A（3，0），则由图象可知，不等式ax2+bx+c＜0的解集是    ．