assurance

certainty, assurance, conviction

这些名词均含有“确信无疑”之意。
certainty: 指在客观上和主观上都无一丝一毫的怀疑。
assurance: 侧重依靠个人力量、本能、方法或对其他人或事的完全信任，强调有信心。
conviction: 多指在理性基础上清除了原有的疑虑或无把握，着重对证据的主观反应。

pledge, guarantee, assurance

这些名词均有“保证，担保”之意。
pledge: 普通用词，指严肃地承诺、信守原则，常以个人名誉作为承诺的保证。
guarantee: 一般指以口头的、协定或合同的形式作为保证、担保，强调口头承诺，含违背许诺，则予以补偿之意。
assurance: 指用语言保证以消除人们思想上的怀疑与担心。

名词 assurance:

1. freedom from doubt; belief in yourself and your abilities
   同义词：self-assurance, confidence, self-confidence, authority, sureness
2. a binding commitment to do or give or refrain from something
   同义词：pledge
3. a statement intended to inspire confidence
4. a British term for some kinds of insurance

1. He made an unctuous assurance.
   他做了个虚请假意的承诺。
2. Marked by assurance, as of success.
   以确信为特征的，如对成功的确信
3. They were waiting with assurance for me to discover the truth for myself.
   他们自信地等待我自己发现事实真相。