[Slgado]

He didn’t visit his uncle because he was ill
(If)

if he hadn' been ill , he would have visited his uncle*
if he had had a good health , he would have visitied his uncle *


If you don the exercise, the teacher will be pleased.
(providing)

the teacher will be pleased , providing that you do the exercise *
او تعكس الجملة زي ما قالت