重晶石砂浆的主要成分是硫酸钡,因此,也叫钡粉砂浆,以硫酸钡为骨料制成的砂浆抹面层,对X光和),射线(伽马射线)有阻隔作用。( )
参考答案:对
( )期间,高速公路建设继续以完善调整公路网络为主。
A.十五 B.十一五 C.十二五 D.十三五
It is reported that the Underground Line No.3 ____ in our city in 2012. [ ]
A. is to build
B. is to built
C. is to be built
D. is to been built