2.7×103 kg/m3=____g/cm3;8.9 g/cm3= _______ kg/m3.
2.7;8.9×103
They are good friends. ____ is no wonder that they know each other so well. [ ]
A. It
B. That
C. There
D. This
铺好的无菌盘有效期为( )。
A.4小时 B.24小时 C.7天 D.14天 E.3天