实验室通常用 称物体的质量．称量一小杯水与一匙盐的总质量，然后再称出盐水的质量，比较两次称量的结果，能得出的结论是：质量与物体的状态 ．
天平；无关
Certainly man must ______ the future, and find ways of providing for his use.
A. look to B. look up C. look for D. look on
什么叫连铸坯中心疏松？
