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【简答题】
有机物A和B的分子量都小于200，完全燃烧时只生成CO 2 和H 2 O，B燃烧时消耗的氧气与生成的二氧化碳的物质的量相等，B中碳、氢元素总的质量分数为46.67%，B不发生反应，但跟NaHCO 3 溶液反应放出CO 2 ，1 mol A水解生成1mol 苯甲酸和1mol B，A溶液具有酸性，但遇FeCl 3 溶液不显紫色。 (1)A与B的分子量之差为_________ 。 (2)B分子中应有_________个氧原子。 (3)A的结构_______或_______。 (4)写出B的属于酯的四种同分异构体的结构_____________。
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【简答题】PLC交流双速电梯,目前层楼指示器普遍采用( )(A)七断数码管 (B)信号灯 (C)指针 (D)发光二极管A.B.C.D. D
【简答题】They aim to bring attention to the fact that there have been few of the disease in the United States. They say there is no reason to avoid Asian American businesses.
【单选题】关于施工缝处继续浇筑混凝土的说法，正确的是（）。
A.
已浇筑的混凝土，其抗压强度不应小于1.0N/mm 2
B.
清除硬化混凝土表面水泥薄膜和松动石子以及软弱混凝土层
C.
硬化混凝土表面干燥
D.
浇筑混凝土前，宜先在施工缝铺一层1：3水泥砂浆
【单选题】关于施工缝处继续浇筑混凝土的说法,正确的是( )。
A.
已浇筑的混凝土，其抗压强度不应小于1.0N/mm2
B.
清除硬化混凝土表面水泥薄膜和松动石子以及软弱混凝土层
C.
硬化混凝土表面干燥
D.
浇筑混凝土前，宣先在施工铺一层1:3水泥砂浆
【单选题】By the fact that he stayed in the United States for more than ten years, he developed an American ________.
A.
stress
B.
sound
C.
voice
D.
accent
【单选题】Each of the following is a valid conclusion from the graphs and the fact that the population of the United States was greater in 1995 than in 1991 EXCEPT
A.
In 1991, s whose highest degree was at least a bachelor's degree were more than twice as likely to participate in educa-tion than those whose highest educational attainment was a high school diploma or GED (high school equivalency diploma).
B.
On a percentage basis, from 1991 to 1995, the greatest increase in the education par-ticipation rate was among those s whose highest educational attainment was grades 9-12, without earning a high school diploma.
C.
In 1995, more people participated in edu-cation programs than in 1991.
D.
From 1991 to !995 the rate of participation in education among the groups represented in the graphs increased the least for those who had attained at least a bachelor's degree.
E.
In 1995, more s with at least a bachelor's degree participated in education than did s who attended some college but did not earn a college degree.
【单选题】关于施工缝处继续浇筑混凝土的说法，正确的是（）。
A.
已浇筑的混凝土，其抗压强度不应小于1.0N／mm
B.
清除硬化混凝土表面水泥薄膜和松动石子以及软弱混凝土层
C.
硬化混凝土表面微湿润
D.
浇筑混凝土前，宜先在施工缝铺一层1：1水泥砂浆
【单选题】关于施工缝处继续浇筑混凝土的说法,正确的是( )。
A.
已浇筑的混凝土，其抗压强度不应小于 1.0N/mm²
B.
清除硬化混凝土表面水泥薄膜和松动石子以及软弱混凝土层
C.
硬化混凝土表面干燥
D.
浇筑混凝土前，严禁在施工缝处刷水泥砂浆
【单选题】关于细石混凝士刚性防水层施工要求，下列说法正确的是 （ ）。
A.
厚度不应小于40 mm， 钢筋网放置在混凝土的中上部，保护层厚度不小于10 mm
B.
厚度不应小于40 mm， 钢筋网放置在混凝土的中下部，保护层厚度不小于10 mm
C.
厚度不应小于20 rnm， 钢筋网放置在混凝土的中上部，保护层厚度不小于10 mm
D.
厚度不应小于30 mm， 钢筋网放置在混凝土的中下部，保护层厚度不小于10 mm
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