A.封鎖作用B.遮蓋作用C.封閉作用D.掩蓋作用
A.0.4?0.5:1B.0.3?0.4:1C.0.2?0.3:1D.0.1?0.2:1
A.7:1.1:8:1:0.7B.7:8:1.1:1:0.7C.7:1.1:8:0.7:1D.7:8:1.1:0.7:1