1. The main field of hygiene is concerned with healthy living and cleanliness.
    卫生学的主要范围和健康的生活及清洁有关。

2. The main field of hygiene is concerned with healthy living and cleanliness.
    卫生学的主要范围和健康的生活及清洁有关。

3. The past forty years saw great success in the control of spreading diseases and great strides toward achieving "health for all by the year 2000" (a major WHO goal) through improved basic health care, food, cleanliness, and immunization(免疫)
    在过去的40年中，通过改善基本医疗保健、食品、卫生和免疫等项目，人类在控制流行病方面取得了巨大的进步，并且朝着实现"2000年人人享受健康"（世界卫生组织的一项主要目标）迈出了一大步。