Between 1897 and 1919 at least 29 motion pictures in which artificial beings were portrayed ______.
A. had produced
B. have been produced
C. would have been produce
D. had been produced
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压缩空气蓄能与抽水蓄能相比弊端是
A. 选择建设地的余地更大
B. 发热使岩石蠕变
C. 装置小
D. 储能密度大
最有利用价值的相变潜热是
A. 固体物质的晶体结构发生变化
B. 固、液相间的相变即熔解、凝固
C. 固相直接变成气相即升华
D. 液、气相的相变即气化、冷凝
下列能源中品相最高的是
A. 电能
B. 机械能
C. 太阳能
D. 热能
下列函数哪种不属于状态函数
A. 压力
B. 时间
C. 体积
D. 焓
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