A.簡單;無須B.簡單;必須C.復(fù)雜;必須D.復(fù)雜;無須
A.凸輪B.挺桿C.搖臂D.彈簧
A.動(dòng)力性B.經(jīng)濟(jì)性C.可靠性D.動(dòng)力性、經(jīng)濟(jì)性、可靠性