The primary aim of this book is to provide students of English as a foreign or second language with an opportunity to do some simple grammar exercises when they have a limited amount of free time, for example whilst waiting for a friend to join them for lunch or whilst taking a short bus journey. The explanations of grammar problems are therefore not extensive.Each entry contains a short explanation on correct usage and is followed by an exercise (usually of ten items). There is an answer key at the end of the book. Sometimes, suggested answers are given where there are many possible answers or where learners have been encouraged to create their own examples.