材料孔隙率的计算公式是P=(1-ρ0/ρ)×100% ,式中ρ为材料的()
You can _____ some bottles of wine, or some chocolates, or a bunch of flowers.
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
2002年新配方口服补液盐(ORS)溶液的张力是
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