であるばかりでなく

not only ... but also

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phrase Rare #40,189
not only ... but also A formal written expression used to connect two qualities or facts, usually followed by でもある or another equivalent expression.
JA: 彼は優れた研究者であるばかりでなく、すばらしい教師でもある。
EN: He is not only an excellent researcher but also a wonderful teacher.

彼は政治家であるばかりでなくさらに立派な学者でもある

He is not only a great statesman but also a distinguished scholar.

シュバイツァー医者であるばかりでなく音楽家でもあった

Schweitzer was not only a doctor but also a musician.

彼女は女優であるばかりでなく有名な画家でもあった

Not only was she an actress, but she was also a famous painter.