Assure vs. Ensure vs. Insure

Basically, the words assure, ensure and insure all mean the same thing: to guarantee or to promise that something is true or that something will happen. But there are slight differences between them:

Assure means to say or write the guarantee:
He assured me that the product would be delivered tomorrow.

Ensure means to do something to make sure or guarantee that something happens:
A firewall helps to ensure that hackers don't attack your PC.

Insure means to guarantee something with insurance or other financial instruments:
In most countries you need to insure your car against accidents.

Note that we use the infinitive "to" before each of these words.

I _____ you that I will finish my report by tomorrow.
They plans to _____ their new house for $500,000.
To _____ good results, follow the directions carefully.
We need to _____ that this mistake never happens again!
The company paid a bribe to the government to _____ that they would get the contract.
Can you _____ me that we won't have any problems with this software?
Although the government would like to _____ the people that terrorists won't strike again, they unfortunately cannot.
They have a quality control department to _____ against too many product defects.
It is very expensive to _____ homes in Florida against hurricane damage.