英语语法分析

The main material of most masks is polypropylene.

大多数口罩的主要材料是聚丙烯。

The paper introduces the anticlastic and water-tight performance of low content polypropylene fiber concrete.

本文介绍了低含量聚丙烯纤维混凝土的抗弹性和防水性能。

Today, surgeons often prefer plastics such as polypropylene.

今天，外科医生们通常选择聚丙烯这类塑料。