A.10%—30% B.15%——45% C.20%—50% D.25%—50%
A.5%B.8%C.10%D.15%
A.星型拓?fù)浣Y(jié)構(gòu)B.環(huán)形拓?fù)浣Y(jié)構(gòu)C.樹形拓?fù)浣Y(jié)構(gòu)D.總線形拓?fù)浣Y(jié)構(gòu)