とは[裏腹「うらはら」] => Contrary to A, opposite of A, ... N1
Contrast/Surprise
…ば…だろう => If ... then perhaps ... N3
Speculation
…ば ... => If... N4
Evaluate
…ば .... => If... N4
Conditions (general conditions)
... ば => If... N4
Condition (hypothetical condition)
… ば .... => If.... N4
Condition (hypothetical condition)
なぜなら(ば)/なぜかというと/どうしてかというと/なぜかといえば => because; the reason is; if you want to know why N3
そういえば => come to think of it; now that you mention it ~ N2
…ば ... => If... then... N4
Condition (hypothetical condition)
…も…ば => just N3
Conditions (necessary conditions)
そういえば => Speaking of .., A by the way, A; N2
Considering, Concerning
ねばならない/ねばならぬ/ねば => have to do; must; should ~ N2