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to mount up; to pile up; to accumulate; to increase
修理費が予想以上に嵩んでしまった。
The repair costs piled up more than expected.
旅行の費用が予想よりずいぶん嵩んだ。
The travel expenses piled up much more than expected.
不況で企業の在庫が嵩んでいる。
Company inventories are piling up due to the economic downturn.