insure vs. ensure 以及 assure

insure v. 确保
ensure v. 确保

很多地方混用，用insure更多一般表示金融财政上的保险

而ensure表示做某些事件的确定性

assure一般只是口头承诺，而不是行动上的。比如I assure you

另外，在听力练习中，注意它们容易和单词issue混淆。

以下转自参考文献2:
Assure is to promise or say with confidence. It is more about saying than doing.
Example: I assure you that you’ll be warm enough.

Ensure is to do or have what is necessary for success.
Example: These blankets ensure that you’ll be warm enough.

Insure is to cover with an insurance policy.
Example: I will insure my home with additional fire and flood policies.

Reference:
[1]http://www.writersdigest.com/online-editor/ensure-vs-insure
[2]http://data.grammarbook.com/blog/definitions/assure-vs-ensure-vs-insure/