In this book, we offer advice that we hope will seem reasonable and worth serious consideration. But as any experienced writer knows, there are occasions when even the best advice may not apply. The demands of writing for different audiences, with different purposes, on different subjects, at different levels of formality are so varied that they cannot begin to be anticipated in a book like this, and we recognize that what is appropriate for one piece of writing may not be appropriate for another. In most cases, you will have to avoid ambiguity at all costs so as not to leave your words open to misinterpretation.