Respuesta :

Answer;
The event in Act IV that foreshadows Macbeth's eventual down fall is that;
Macduff discovers Macbeth has murdered his family and vows to kill Macbeth himself. This  is used to foreshadow an imminent conflict between Macbeth and Macduff.

Explanation
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Foreshadowing is the use of indicative word or phrases and hints that set the stage for a story to unfold and give the reader a hint of something that will happen without revealing the story, or interfering with suspense. 

Answer:

Macduff discovers Macbeth has murdered his family and vows to kill Macbeth himself.

Explanation:

Foreshadowing is a literary device in which a writer gives a hint of what is going to happen later in the story. Foreshadowing helps the reader develop expectations about the upcoming events of a story. Foreshadowing is also a useful device to create suspense and dramatic tension. This event shows that Macduff has discovered Macbeth's actions, and it hints towards an eventual conflict between Macduff and Macbeth.