萤石化渣作用快,且不降低炉渣碱度,因此,对炉龄没有影响。
参考答案:错
实践是人类认识的来源和检验认识真理性的标准之一。
Quality of the present shipment is equal to () of last consignment.
A. this
B. these
C. that
D. those