ことはない => Not necessary N3
Needs, Requirement
とは[裏腹「うらはら」] => Contrary to A, opposite of A, ... N1
Contrast/Surprise
ことは~が => Although A is true, C N3
Contrast
どころではない => Its not A N2
Contrast,Surprise
ことなしには => Without doing A, B N1
Conditional, While
ことから => Displays reason A for effect B N2
Reason, Result, Response
に[越「こ」]したことはない => It's better if A, it's better if it's A N1
Comparison/ Exchange
とは限らない => A is not 100% N3
Information, Report
ずにはいられない/ないではいられない => Can't help but A; A is unavoidable N2
Will, Decision, “Doing”
ことだから => Shows a typical trait or characteristic of A N2
Information, Report
ということは => A In other words, B; A Oh, so B N2
Adjectival, Descriptions
とはくらべ[物「もの」]にならない => It's no match for A N1
Comparison/ Exchange