This rule is valid only when the "d" is located within a word. -eDificio (building) -aDorar (to adore)

The Spanish "d" has two separate sounds, hard and soft. At the beginning of a word and after "n" or "l", the hard Spanish "d" closely resembles the "d" in the word "dog." The difference is that when pronouncing the hard Spanish "d", the tongue touches the back of the front teeth (rather than the gum ridge, as in English). In other situations (particularly between vowels) the "d" is softer, closely resembling the "th" sound in the word "this."