The negative proposition is only put forward for the case that P is Q, and its negative proposition is actually the case that P is not Q, and the true value of the negative proposition has nothing to do with the original proposition.

The negation of proposition is: proposition P, negation is not P, and negation is definitely true or false.

What you put forward, if P is Q, its no proposition is not mentioned, as I said before. Its negation only negates the conclusion that if P is not Q. ..

For negative and negative propositions. Just remember, negation only negates the conclusion, and whoever is the conclusion will be denied. The negative proposition is negative at the same time, that is, the conditions and conclusions are negative at the same time. Among the questions you gave, proposition Q is obviously a false proposition. Its negation is: If a>b, then Sina ≤sinb. No proposition is a≤b, then sina≤sinb.

False proposition. Y=sinx is a sine function with periodicity, and it is impossible to compare sizes without defining the domain.