Both strains quickly invaded local hospitals when needle sharing and other unhealthy practices ensured the rapid spreading of the infection by bringing people into contact with contaminated body fluids.
出自-2013年6月听力原文
柯林斯高阶英汉双解学习词典释义
VERB
保证;确保;担保
To ensure something, or to ensure that something happens, means to make certain that it happens.