A.一級維護 B.日常維護 C.二級維護 D.三級維護
A.效率高 B.經(jīng)濟性差 C.結(jié)構(gòu)復(fù)雜 D.自動適應(yīng)性能好
A.20° B.10° C.15° D.30°