if i came home later my mother would be angry.

if he had known my address we would have visited me yesterday.

i was not well prepared for the examination. I wish I had worked harder.

if i had seen you yesterday I would have told you about it.

if i had known that you needed my help I would have helped you.

if i were in your place I would buy another model of the mobile phone.

if i had a computer I would write the report faster.