英语语法分析

As an additional safeguard against weeds you can always use an underlay of heavy duty polyethylene.

作为另外一种预防杂草的防护措施，你可以一直使用一层厚重耐磨的聚乙烯底垫。

《柯林斯英汉双解大词典》

Press the seam open and carefully align the underlay before pinning the right sides together.

正面合在一起之前，先将缝线烫开并仔细地将缝的粗缝线。

Objective To explore Hydrogels underlay in preventing bed sore of orthopaedic surgery patient.

目的探讨水凝胶垫在预防骨科手术患者压疮的护理。