Charlemagne was the greatest Frankish king, who founded the first empire in Western Europe after the fall of Rome。()
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在机械通风和自然通风的烟囱各起什么作用?其高度根据什么原则确定?
The Hammurabi Code is the oldest known legal document in human history。()
什么叫自生风?自生风的正负号如何决定?在水平烟道有没有自生风?
The Minoan civilization is often regarded as the first advanced civilization of Europe。()