背景可起（）的作用。
A.美化主体
B.吸引视线
C.烘托主体
D.烘托陪衬
参考答案：C
(2014·皖南八校联考)________ Yao Ming has retired from the NBA，the pleasure we have got by watching him play basketball at home and abroad will last long.
A．Although
B．If
C．Since
D．Once
一单层建筑物天棚净高6.8m，顶棚粉刷搭设满堂脚手架，其增加层数为( )层。
A．1B．2C．3D．4
