I am currently checking out websites looking for German-English exercises. I found several "suppliers" who sell PDF files of exercises to teachers and pupils. Very useful stuff, these sites usually have a few sample exercises, so you get an impression what kind of material you're paying for. One such sample exercise was this:
Change into simple past: Children don't have to go to school, so not many people can read or write. There are some famous boys' schools in London, but only rich men's sons may go there. These boys can get their books from a new bookshop in the city, but they are expensive.
Correct answer: (Children didn't have to go to school, so not many people could read or write. There were some famous boys' schools in London, but only rich men'sons might go there. These boys can get their books from a new bookshop in the city, but they were expensive.)
Uh-huh. Sloppy, very sloppy.
Change into simple past: Children don't have to go to school, so not many people can read or write. There are some famous boys' schools in London, but only rich men's sons may go there. These boys can get their books from a new bookshop in the city, but they are expensive.
Correct answer: (Children didn't have to go to school, so not many people could read or write. There were some famous boys' schools in London, but only rich men'sons might go there. These boys can get their books from a new bookshop in the city, but they were expensive.)
Uh-huh. Sloppy, very sloppy.