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The Development of Rubber Here is the story of rubber. From the earliest time it was common knowledge {{U}} (51) {{/U}} the Peruvians that when a cut was made in the outside skin of a rubber tree, a white liquid {{U}} (52) {{/U}} milk came out, and that {{U}} (53) {{/U}} this a sticky (粘的) mass of rubber might be made. This rubber is soft when warm, so that it is possible to give it any {{U}} (54) {{/U}}. The Peruvians made the {{U}} (55) {{/U}} that it was very good for keeping out the wet. Then in the early 1800’s, the Americans made use of it for the first time. First they made overshoes to {{U}} (56) {{/U}} their feet dry. Then came a certain Mr. Mackintosh, who made coats of cloth covered with natural rubber. From that day to this we have been coating cl A. capable B. probable C. practical D. possible [多选题]航空器活动区驾驶机动车辆的驾驶员不得对失效的机动车号牌、驾驶证、行驶证、车辆通行证进行哪些行为,正确的是?()
A.涂改 B.伪造 C.挪用 D.骗取 [单选题]单机挂车在区间被迫停车后的防护工作由（ ）负责，开车前应确认附挂辆数和制动主管贯通状态是否良好。
A.机车乘务组 B.车辆乘务员 C.车站人员 [单选题]捣固车一次拨道量不宜超过（ ）mm，曲线地段上挑、下压量应接近。
A.100 B.80 C.40 D.50 [单选题]消防人员、事故处置人员必须着避火服、进入火区着( )，以防被火烧伤。
A.隔热服 B.防辐射服 C.防静电服 D.防酸碱服 [单选题]我国水旱灾害常见的类型有洪水、山洪、( )等。
A. 干旱 B. 旱灾 C. 暴雨 D. 雪灾 [单选题]加、减速顶区( )使用铁鞋制动。
A.可以 B.不能 C.不得 D.禁止 [单选题]上级漏电保护器的额定漏电流应比下级漏电保护器的漏电流( )。
A. 大 B. 小 C. 相等 D. 随意 [单选题]基岩水准点，宜选在基岩露头或距地面不深于m的基岩上。( )。【该题涉及5.2内容】
A.3m B. 4m C.5m D 6m [单选题]截肢者康复治疗中，术后全身性治疗包括( )
A.早期截肢者的心理治疗 B.术后无假肢适应性训练 C.术后尽早进行肢体运动 D.术后生活能力的指导 E.以上都是 [单项选择] 阅读下面这篇短文，短文后列出了7个句子，请根据短文的内容对每个句子做出判断。
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