阅读下列材料：

材料一：大会（中共八大）正确地分析了国内形势和国内主要矛盾的变化，提出了党在今后的根本任务。刘少奇的政治报告，不仅系统地论述了以《论十大关系》为中心的一系列方针政策，而且进一步提出和解决了一系列战略问题。大会关于政治报告的决议明确指出：我们党已经领导人民取得了对农业、手工业和资本主义工商业的社会主义改造的全面的决定性的胜利。

——胡绳《***七十年》

材料二：脚踏黄河水倒流，搬来泰山做枕头；决心苦干十五年，赶上英国不发愁。

材料三：热热闹闹的公社食堂松松垮垮的田间劳动

材料四：随着农村经济体制的改革，现行农村政社合一的体制显然很不适应。宪法已明确规定在农村建立乡政府，政社必须相应分开。

——引自〈中共中央、国务院关于实行政社分开建立乡政府的通知〉（1983年）

假如代生活在东汉末年，你认为当时的最高成就有（　　）

①蔡侯纸   ②麻沸散   ③《九章算术》  ④四诊法

曲线的极坐标方程$\rho =4\sin \theta$化成直角坐标方程为(    )

一篮球运动员投篮一次得3分的概率为a，得2分的概率为b，不得分的概率为c，其中$a,b,c\in (0,1)$，且无其它得分情况。已知他投篮一次得分的数学期望为1，则$ab$的最大值是（　）

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