"She orders a cup of tea."
Translation:Ŝi mendas tason da teo.
Never accusative after da, and only in some rare cases after other prepositions.
If she were at the coffee shop and she ordered a cup of tea, rather than coffee, would an observer not say, "tason de teo"?
I'm interested in knowing why the answer has to be a cup of tea. If we want to get specific, the lady isn't ordering a cup, rather tea. So would an appropriate answer be "Ši mendas teon en taso" ?