For example:

Original proposition: for any x belonging to r, sinx

No proposition: existence x does not belong to r, sinx & gt 1

Negative: existence x belongs to r, sinx & gt 1

Note that "being" or "for any" is also part of the conclusion, and vice versa.

For example, it is enough to deny that "our class is all boys" and give an example that "so-and-so in our class is a girl", instead of saying that "our class is all girls"

Original proposition: if q

There is no proposition: if q> 1, then x 2+2x+q = 0 has no real root.

Negative: if q

Note: the original proposition and the negation of the proposition must be true and false, and there is no connection between the truth of the original proposition and the truth of the proposition.