彩釉砖的吸水率不大于()。
A.10%
B.18%
C.20%
D.15%
参考答案:A
In more recent years,()has been used by civilians in many new ways to determine positions,such as in automobile and boat navigation,hiking,emergency rescue,and precision agriculture and mining.
A.GPS
B.GMDSS
C.AIS
D.Navtex
UPEU的主要功能有哪些?