"Ha comido" es el indicativo. "Miguel ha comido." Miguel has eaten. "Es obvio que Miguel ha comido." It is obvious that Miguel has eaten." "Haya comido" es el subjuntivo, utlizado en una cláusula subordinada que requiere el subjuntivo: "Es dudoso que Miguel haya comido." It's doubtful that Miguel has eaten. "Es posible que Miguel no haya comido." It's possible that Miguel hasn't eaten. David, if you're unsure of the terms "Indicative" and "Subjunctive" then this might not make much sense to you. The Indicative Mood is generally used to express factual statements. The Subjunctive Mood is used to express emotion, doubt, command and hypothetical situations. In short, the reason why "haya comido" was used in the last two examples was because expressing that something is doubtful (Es dudoso) or possible (Es posible) introduces the following clause as a hypothetical situation. Therefore "haya" (present subjunctive of haber) was used rather than "ha". ¡Ojalá que te haya ayudado! (I hope (emotion) that I have helped you!) Richard