Answer:
she didn't want to kill Duncan because killing him would seem as if she killed her own father and that decision would give her nightmares
While the main idea is usually in the first sentence, the next most common placement is in the last sentence of a paragraph. The author gives supporting information first and then makes the point in the last sentence. Here's a paragraph we can use as an example. Try to locate the topic and the main idea.
Answer:
there are no words or meanings
1: Are
2: Is
3: are
4: are
5: don't