A.background-position:rightbottom; B.background-position:righttop; C.background-position:leftbottom; D.background-position:lefttop;
A.opacity:0.5; B.filter:alpha(opacity=50) C.background:rgba(0,0,0,.5) D.background:opacity(0,0,0,.5)
A.1000 B.100% C.內(nèi)容寬度 D.600