单项选择题
A.3170元/吨,3180元/吨,3020元/吨 B.3220元/吨,3180元/吨,3040元/吨 C.3220元/吨,3260元/吨,3400元/吨 D.3270元/吨,3250元/吨,3100元/吨
A.8 B.-8 C.4 D.-4
A.67800元/吨,69300元/吨,69700元/吨 B.67680元/吨,68930元/吨,69810元/吨 C.68200元/吨,70000元/吨,70000元/吨 D.68250元/吨,70000元/吨,69890元/吨