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什么是种子标签制度？
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当设备需要恒速、大功率长期连续工作时，应使用异步电机作动力设备。
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下列各项中，应计入营业外支出的是()
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墙体开裂质量事故产生的原因可能是设计计算有误，计算简图与实际受力不符，地基不均匀沉降，或温度应力，冻胀力的作用，也可能是施工偷工减料、材料不良等造成。由此可体现出建筑工程质量事故的（）。
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直流电引起烫伤的原因是（）
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下列哪项不是人类嗜T淋巴细胞病毒Ⅰ型和Ⅱ型的传播途径（）。
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Quotas , tariffs and subsidies Like most wars,a trade war may bring about desired economic or political changes, but in the long run almost everyone suffers ,including those whom the trade war was meant to help. An efficient carmaker, for example, may ask for limits of foreign imports, hoping to keep its price high without improving the quality of its products. In the end , however , other countries may retaliate with trade restrictions of their own. Consumers and businesses in both countries are then forced to buy poorly made and expensive domestic products. Trade restrictions might protect a few jobs in inefficient industries,but the whole economy often suffers by becoming less competitive in the international markets. The most common tools for limiting imports of foreign goods and services are quotas, tariffs,and subsidies. When a country imposes a quota, it limits the quantity of certain foreign products that can be imported. A tariff is a tax placed on goods entering a country , raising the price of imported goods. A government can also use the taxpayers' money to provide a subsidy to local producers , making the price of local goods artificially lower than imported goods. Trade barriers, like walls between feuding neighbors, are usually imposed unilaterally by one country acting on its own to limit the amount of foreign products available to local producer from foreign competition and allow them time to improve their products or lower their prices as long as they are protected from foreign competition by trade barriers. Although trade restrictions are of dubious economic value, they have been shown to be effective in bringing about political or social change. The refusal of countries to trade and do business with South Africa, for example, was widely seen to be responsible for the decision to dismantle the system of apartheid. Trade blockades can be useful in forcing countries to change policies that violate human rights or international treaties, but as long as a sufficient number of countries join in the blockade to make it effective. Questions for reading :
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测烟望远镜法测定烟气黑度时，观测者可在离烟囱（）m远处进行观测。
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阐述柴油机冷却系统的组成及各部分的作用。
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患者，女性，45岁。有糖尿病史。主诉外阴瘙痒，妇科检查：白带豆腐渣样，阴道壁充血，宫颈光滑。如果分泌物检查发现菌丝和芽胞，宜选择的药物治疗是（）