生产者价格指数(PPI)是用来衡量生产成本变化的指数,它的计算中仅考虑有代表性的生产投入品,如原材料、半成品和工资。()
参考答案:对
As we all know, tigers and cats________the same family of beasts. [ ]
A. belonged to
B. are belonged to
C. belong to
D. are belonging to
科学具有连续性、深入性和创造性的特点。