…のも無理 (は) ない => It's natural for... N3
Evaluate
決して~ない => never; by no means ~ N3
のも無理もない => (to be) natural,(to be) understandable N3
Evaluate
[決「けっ」]して~ない => Won’t, isn’t N3
Will, Decision, Doing
に決まっている => certainly; I’m sure/certain that; it must be the case that ~ N2
に[決「き」]まっている => A is a given, A must be the case N2
Information, Report