Logic Course Worksheets added

Some worksheets have now been added to the first three sections of my course on logic.

I have also updated the front pages of my papers with guidance notes to remind students that my mock papers contain only hard, very hard, and occasionally unreasonably hard questions :). The routine and easier material has been deliberately left out, so students should not be discouraged if they find the papers difficult or need longer than the recommended time.

The main aim of these papers is improvement rather than measurement: meet difficult problems, struggle with them, learn from them, and get better each time!