Hello EdwardWu: I can answer you these two questions. If you read it in English, are very easy to understand. 1) Dígame qué número calza usted (Tell me what shoe size you normally wear). In this sentence I'm asking you to tell me what shoe size you normally wear in order to me to show you the right size for you. It's the question that a shoe salesman makes to a customer. A verb is "tell" and the other "wear". 2) De ese modelo sólo queda un par grande (There is only one large pair of this model). The meaning of "De" in this sentence is like in English "Of". "de ese modelo" = "of this model". I sincerely hope this helps, EdwardWu.