There is no doubt that spaceflight entails risks, and to pioneer a new mode of travel is to face those risks, and to reduce them with the benefit of hard-won experience.
2015年12月六级真题（第二套）阅读 Section C
柯林斯高阶英汉双解学习词典释义
VERB
使…必然发生;势必造成；使…成为必需
If one thing entails another, it involves it or causes it.