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| Subject | English | Russian |
| comp. | when the need arises | при возникновении необходимости (This would entail participating in its meetings and activities, providing information and advice and exercising good offices when the need arises. RealMadrid) |
| law | when the need arises | по мере необходимости (Leonid Dzhepko) |
| gen. | when as, if the need arises | по мере в случае необходимости |
| gen. | when the need arises/arose | по надобности (Liv Bliss) |