Read it through once

“Impossible!—I never can call you any thing but ‘Mr. Knightley.’ I will not promise even to equal the elegant terseness of Mrs. Elton, by calling you Mr. K.—But I will promise,” she added presently, laughing and blushing—“I will promise to call you once by your Christian name. I do not say when, but perhaps you may guess where;—in the building in which N. takes M. for better, for worse.”