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超声波的物理特性中，"介质的密度与声速的乘积"属于（）超声波的物理特性中，"在单位时间内声波在介质中传播的距离"属于（）超声波的物理特性中，"如果两种介质的声阻相差很小，能量反射就很小，绝大多数超声波进入第二介质"属于（）超声波的物理特性中，"指超声波在介质中的传递"属于（）超声波的物理特性中，"温度增高时超声波的传播速度加快"属于（）超声波的物理特性中，"超声波在不同介质中传播时，一部分超声波被界面反射回到原来的介质中"属于（）超声波的物理特性中，"超声波在不同介质中传播时，一部分超声波被界面反射回到原来的介质中，剩余部分超声波穿透界面进入另一种介质，但传播方向发生改变"属于（）
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烈士和因公牺牲的现役军人，一次性抚恤金标准为上一年度全国城镇居民人均可支配收入的40倍加本人40个月的工资。
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正常工作状态下在一个基波周期中，开关动作频率最高的是()。
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法国葡萄酒的等级是依据（）划分的。
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表征压电材料的参数是（）（），K值恒小于1，它是压电材料进行（）的能力反映。
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A few years ago , a sad thing happened. A young American woman left her 21_______for career reasons; she moved far away. For this reason ,a 36-year- old 22_______father has custody of his two children , eleven and eight years old. He works long hours as a 23_______, including weekends. On his days off from work , he goes to a local 24_______college. He' s studying to 25 his job skills so he can make more money for his family. At night he does his homework at the same table as the 26_______. But who takes care of the kids in the evenings when their father is working or 27_______to school? His "extended family"- his mother , other 28_______, and his new girlfriend 29_______out as much as they can. He thinks his girlfriend , who is from Mexico , his home country , is good for his family. He doesn’t want to date "Anglos"or"Anglicized" women because he thinks they value their 30_______over motherhood. He wants a wife with traditional , religious values like his mother.
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关于脉络膜哪项错误（）。
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我国南北走向的国道是以（）字开头的三位数字表示。
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不属于学习美学的有利作用是（）
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甲公司欠乙公司500万元货款未付。丙公司是甲公司的母公司。甲公司与丙公司订立协议，约定将甲公司欠乙公司的该笔债务转移给丙公司承担。下列关于甲公司和丙公司之间债务承担协议效力的表述中，正确的是()。