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(not) always; (not) necessarily; (not) entirely; (not) all
高いからといって必ずしも良いとは限らない。
Just because it's expensive doesn't necessarily mean it's good.
努力が必ずしも報われるわけではない。
Effort doesn't necessarily pay off.
彼の意見が必ずしも正しいとは思わない。
I don't think his opinion is necessarily correct.