In our school library there a number of books on science and the number of them growing larger and larger.
A:is,are
B:are, is
C:has,is
D:have,are
目前石家庄市正在进行地铁建设,广泛使用金属材料,下列不属于合金的是( )
在国际单位制中,力的单位是( )