构造原理揭示的电子排布能级顺序,实质是各能级能量高低。若以E(nl)表示某能级的能量,以下各式中正确的是( ) A.E(5s)>E(4f)>E(4s)> E(3d) B.E(3d)>E(4s)>E(3p)>E(3s) C.E(4s)<E(3s)<E(2s)<E(1s) D.E(5s)>E(4s)>E(4f)>E(3d) 答案:BIf you ___________ in the exam, you will let your parents down. A.fall B.will fall C.fail D.will fail