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[单选题]AC006对于90°薄板折角弯曲件(R内/t<0.5)它的展开料长计算可按板厚中心线长度相加,另外,每弯曲一个折角减去( )。
A.0.25t B.0.5t C.1t D.2t [简答题]如何让大企业有创新动力？
[判断题]纵梁长度等于主桁架节间长,它的两端用连接角钢和横梁相连。
A.正确 B.错误 [判断题]尾矿坝的位移观测在汛期应加大观测频率。（ ）
A.正确 B.错误 [单项选择]软件工程的结构化生命周期方法，将软件生命周期划分为计划、开发和运行三个时期，下述哪项(些)工作应属于软件开发时期的内容
Ⅰ．需求分析 Ⅱ．可行性研究 Ⅲ．总体设计 A. Ⅰ B. Ⅰ、Ⅱ C. Ⅱ、Ⅲ D. Ⅰ、Ⅲ [单选题]接触网倒闸作业执行一人操作、一人( )制度。
A.辅助 B.防护 C.监护 [单选题]关于地球同步(或静止)卫星说法正确的有( )
A.位于地球赤道上空,高度 36000 千米左右 B.与地球自转速度相同,在赤道上空静止不动 C.也称地球同步轨道卫星 D.以上全对 [单选题]某企业2007年第一季度利润上升了38. 7万元，第二季度利润下降了18. 4万元，第三季度利润上升了51. 3万元，第四季度利润上升了28. 4万元。则该企业2007年的总利润上升了（ ）。
A.90万元 B.100万元 C.110万元 D.136. 8万元 [判断题]小阻力扣件使用的复合垫板，橡胶与不锈钢片分离时不必及时更换。
A.正确 B.错误 [判断题] 二氧化碳焊不能焊接薄板。 ( )
A.正确 B.错误 [单项选择] The use of heat pumps has been held back largely by skepticism about advertisers’ claims that heat pumps can provide as many as units of thermal energy for each unit of electrical energy used, thus apparently contradicting the principle of energy conservation.
Heat pumps circulate a fluid refrigerant that cycles alternatively from its liquid phase to its vapor phase in a closed loop. The refrigerant, starting as a low-temperature, low-pressure vapor, enters compressor driven by an electric motor. The refrigerant leaves the compressor as a hot, dense vapor and flows through a heat exchanger called the condenser, which transfers heat from the refrigerant to a body of air. Now the refrigerant, as a high-pressure, cooled liquid, confronts a flow restriction which causes the pressure to drop. As the pressure falls, the refrigerant expands and partially vaporizes, becoming chilled. It then passes through a second heat exchanger, the evaporator, which transfers heat from the air to the
A. explain the differences in the working of a heat pump when the outdoor temperature changes B. contrast the heating and the cooling modes of heat pumps C. describe heat pumps, their use, and factors affecting their use D. advocate the more widespread use of heat pumps [单项选择]裂解细菌的试剂是（）
A. SDS B. EDTA C. 异丙醇 D. 75%乙醇 E. 无水乙醇 [单选题] 施工升降机的防坠安全器应在标定期限内使用，标定期限不应超过（ ）。
A. 一年 B. 半年 C. 两年 D. 3个月 [单选题]适合微波消毒的物品是 ( )
A.弯盘 B.体温计 C.血压计 D.血管钳 E.塑料奶瓶 [单项选择] 阅读下面文章后回答问题：
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