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to melt into; to dissolve into; to merge into
to blend into (surroundings); to fit in; to adapt to; to integrate
スプーンでかき混ぜて砂糖がコーヒーに溶け込んでいる。
The sugar dissolved into the coffee.
転校してきたが彼はすぐに新しい環境に溶け込んだ。
He blended into the new environment.
新しい環境に溶け込めた。
I was able to blend into the new environment.