[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
における => in; at (place) N2
Scope
に[決「き」]まっている => A is a given, A must be the case N2
Information, Report
手前 => considering; before; in front of; one’s standpoint N1
ひとつには…ためである => Partly because of ... N3
Cause, reason
のが上手 => to be good at doing something N5
のが下手 => to be bad at doing something N5
決して~ない => never; by no means ~ N3
...かける => Impact N3
Act
~ためしに…てみる => to attempt, to test, to try out N1
Invite and advise
なければならない/なくてはならない/なければいけない/なくてはいけない/なければだめ/なくてはだめ => must N5