1, It was my secrectary who sent the bill to Mr Harding yesterday.
It was the bill that was sent to Mr Harding by my secretary yesterday.
It was Mr Harding whom was sent the bill by my secretary yesterday.
2, It was my wallet that was lost somewhere in there.
3, It was my teacher who helped me a lot with my study last semester.
It was me that was helped a lot with my study last semester by my teacher.
4, It was Tam who was given a bicycle as a scholarship by the headmaster.
It was a bicycle that was given to Tam as a scholarship by the headmaster.