Question

The work was done in my presence change it to complex sentence

Answer 1

A sentence which contains subordinate clause(s) reffered as complex sentences.

There must be one independent clause along with atleast one dependent clause.

For ex: I was present when work was going on can be reframed as complex sentence - When the work was on, I was present.

Answer 2

when the world was on I was present

or

I was present when work was going on