【求助】这句话怎么译啊,谢谢帮译请进

The item to be permanently sew down is the bulk (植物学中是球茎). 绒花(Felt Flower)上的球茎应是小绒球做的。 Therefore:
Alternative translation:
绒花上的小绒球要牢固地缝在连衣裙和假发上, 并能经得住21磅的拉力。

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在测试上, 21 lb 较为少见. May be, it was converted from kgf or N; or a typing error (2 lb?)