He played a supplementary role for the plot.

他在小说中只起情节铺垫的作用。

youdao

Nevertheless, foreign aid can only play a supplementary role.

但是，无论如何，外援只能起辅助的作用。

youdao

GIS plays more and more important supplementary role in transport because of improvement of GIS.

随着GIS技术的实用性不断提高，GIS在交通领域发挥着愈加重要的辅助作用。

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