—Let's go to watch the cosplay show!—Sorry, I . I have to go to my guitar lesson.
A：shouldn't
B：mustn't
C：needn't
D：can't
Because Sarah has always saved __________, she is now able to afford a big house.
公元前5世纪中叶，雅典基本形成了一项由富人承担的“为公众办事”的捐献制度。“富有阶层对荣誉的热望促使他们频频自愿承担公益捐助，而且这种捐助有时会给他们带来实质性的回报。”由此可见，雅典的“捐献制度”（ ）
抛物线y=x2﹣4x+c与x轴交于A、B两点，已知点A的坐标为（1，0），则线段AB的长度为____ ．
