a firm statement that sth is certainly true or will certainly happen; promise
confident belief in one's own ability and power
insurance against events that are certain rather than possible
"his assurance in his superiority did not make him popular"
"after that failure he lost his confidence"
"she spoke with authority"
"an assurance of help when needed"
"signed a pledge never to reveal the secret"
"the President's assurances were not respected"
But yet I'll make assurance double sure And take a bond of fate.
出自：Macbeth , Shakespeare
He spoke with assurance, but I could see the dawning of a doubt in his mind.
出自： J. Buchan
Like an ignorant fighter..he is exultant in the assurance of his knowledge and his power.
出自： T. C. Wolfe