你可能感興趣的試題

A.select*from scott.wz where wunit is null and rownum＜5；
B.select*from myuser.wz where wunit = null and rownum＜5；
C.select*from myuser.wz where wunit is null and rownum＜6；
D.select*form scott.wz where wunit is null and rownum＜6;

A.雙絞線
B.同軸電纜
C.光纜
D.無線介質(zhì)