The rule of thumb is that in English the direct object/Akkusativobjekt doesn't get a preposition, while the indirect object/Dativobjekt gets (or may get) "to", e.g. "jemandem (Dativ) etwas (Akkusativ) geben/schenken" - to give something/a present to someone "jemandem etwas leihen" - to lend something to someone "jemandem etwas sagen/erzählen" - to say/tell something to someone "jemandem etwas zeigen" - to show something to someone Unfortunately, this doesn't always work. The only way to make sure that you get it right is to learn the appropriate case/s together with the verb.