2011年，长沙成功获得哪里批准的国家先进电池材料及电池高新技术产业化基地？
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某企业只生产一种产品，单价5元，销量100件，变动成本率30%，则贡献边际为（）。
整个或部分转体过程中，任何用全脚完成的转体或姿势不准确均不处作转体难度。
A. 正确
B. 错误
For a continuous operation diesel engine, a duplex filter unit would be the best arrangement because （）.
A. changing filter elements would not interrupt engine operation
B. filtering occurs twice in each pass of oil through the system
C. clogging will not occur
D. dropping pressure is half of that through a single filter unit
林分平均高比林分优势木平均高受抚育间伐措施的影响大
A. 正确
B. 错误
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