题目

质子数和中子数相等的原子R其质量数为A，则W g该原子形成的阴离子Rn-含有电子的物质的量为(    ) A.W(A／2+n)／A mol                B.W(A／2-n)／A molC.Wn／A mol                            D.A(A／2+n)／W mol 答案：A—Yesterday, I read White Night by Higashino Keigo. Such a good book!—________. No one can match Higashino Keigo in artistic talent.A. You said itB. You don’t sayC. You can’t be seriousD. You set me up