Final answer:
Macbeth's doubts in lines 51-76 include his loyalty to Lady Macbeth, his ambition and the consequences, and his trust in the witches' prophecies.
Step-by-step explanation:
In lines 51-76 of Macbeth, Macbeth expresses several doubts and concerns that are troubling him:
- His loyalty to Lady Macbeth: Macbeth is worried about whether he can go through with their plan to kill King Duncan without wavering or showing any signs of doubt or fear.
- His ambition and the consequences: Macbeth is concerned about the consequences of his ambition to become king. He wonders if it is worth it to commit murder and bring chaos to his life and kingdom.
- His trust in the witches' prophecies: Macbeth questions whether the prophecies of the witches are reliable and if they can be trusted. He is unsure if they are leading him to his ultimate downfall.