The Oxford Guide to English Grammar PDF Free Download
A useful feature of the book is the inclusion of example texts and conversations, many of them authentic, to show how grammar is used in connected writing and in speech.
Language changes all the time. Even though grammar changes more slowly than vocabulary, it is not a set of unalterable rules. There are sometimes disagreements about what correct English is and what is incorrect. 'Incorrect' grammar is often used in informal speech. Does that make it acceptable? Where there is a difference between common usage and opinions about correctness, I have pointed this out.
This information is important for learners. In some situations it may be safer for them to use the form which is traditionally seen as correct. The use of a correct form in an unsuitable context, however, can interfere with understanding just as much as a mistake. To help learners to use language which is appropriate for a given occasion, I have frequently marked usages as formal, informal, literary and so on. You can download this book from the below mentioned link in Pdf format to learn offline.