What is Sufficient Causes?

[House]

I understood Necessary and Contributory Causes.

Necessary Causes: Emergence of Cause A is a condition for leading Result B
For example: General Paresis (Result B) must develop a person infected syphilis

Contributory Cause: The cause A is not the necessary condition
but increase the chance for the result B
Example : Parental rejection could increase the chances of developing the depression in later stage.

My question is , what is sufficient causes, what are different between necessary causes?

Thanks!