Well the expert goofs, but being an expert catches it -- right after she saves it!! (or she's sly, trying to make you see such errors) Did you catch it? There was a phrase put in the wrong place, so it sounds as if I'm writing about a dictionary with d's and t's in between vowels (as in seating and seeding), but I'm talking about those letters in words in the dictionary. If you didn't catch it, be warned!! You don't want to do that. It brands you as a poor communicator!!!!
Tip for today: to avoid using a d for a t or vice versa, often a related word is your clue. You know it should be batter, not badder, because a batter is one who bats. You know it should be sitting not sidding because you sit, so, in adding the ing ending, you still use t. It's a wedding if people wed, but it's a wetting agent if it gets something wet. Wherever possible, and admittedly, it's not always possible, think of the word within the word. Sorry, but for words like lady and city that don't have related words, you're just have to go back and memorize them.