EXPRESSING CERTAINTY

Theory
To express the faith that something has been/ is being/ will happen, use the following phrases :
-I'm sure : Saya yakin
-I absolutely sure : Saya benar-benar yakin
-I'm certain : Saya yakin

Example
If you have question :
"Will Amir pass the exam?" = "Apakah Amir akan lulus ujian?"
Can respond with :
-"Yes, I'm sure he will" = "Ya, saya yakin dia akan lulus"


Courtesy By : http://spensaguti.wordpress.com/2013/09/12/expressing-certainty-and-uncertaintydoubt/