Business Basics (old edition)
Despite the name, this book is most suitable for Pre-Intermediate or even low Intermediate students. For such students, its main selling point is that it has a very clear and progressive grammar and functions syllabus (not always the case with Business books) so the students can see the progress they are making. This does mean it is difficult to skip chapters etc for students who need something in the later chapters for a conference next week, so it best for very general Business students, especially pre-experience, rather than ESP students.