Proofreading

I work as an online English teacher, and one of my students is preparing for a fairly high level job interview in English. Part of it is to write a report which he'll need to present and he's under a lot of time pressure. 

I spent an hour this afternoon proofreading and correcting his report, off the clock as a favour, so that I could get it back to him in time for him to review before we start working on his presentation in tomorrow's class. 

To be honest I wasn't expecting it to take me so long, but it was completely impenetrable text about accounting standards and I had to read it about 10 times just to understand it!