单项选择题
A.700hPaB.600hPaC.500hPaD.400hPa
A.5.7~7.3umB.10.3~11.3umC.0.52~0.75umD.11.5~12.5um
A.3级B.4级C.6级D.8级
A.3×3B.5×5C.7×7D.9×9
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