Frankenstein
Foreshadowing is the act of presenting materials that hint at events to occur later in the story. In chapter 21, the murder of Clerval is disclosed. Find a passage that foreshadows this information.
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I recall that around Chapter’s 18 Henry Clerval enjoys beauty of nature (as does the monster) which foreshadows Clerval's death. I don't have the book with me but you can scan Ch. 18 and I think it is there.