can any one tell me the best book for english

First of all to make ur english section strong u have to read newspaper or magazine dialy and Secondly there were many books which help u but i recommend u Wren N Martin . This is one of the book which is going to rectify your grammatical errors if you read the rules carefully and follow it in your speaking. The chapters are given in a proper order from basics to a difficult level. There are exercises in the end of every chapter so that you can be thorough with what you have read in the entire chapter.. :)