I Want a Very Good Grammar Book in PDF Format Easy Language?

I want a very good grammar book in PDF format easy language. I am confused about all tenses clause structures. What is the best free website so that I can improve my English writing, especially?

This depends somewhat whether your goal is to become an English pedant, that is, one who is pedantic about the subject or simply want a familiarity with English that minimizes error. For a start, error becomes custom through regular use and drives the pedant to sleeve ripping and tearing out their hair in frantic handsful. Take note of that word, handsful, One L and it is the hands that are plural, not the fulls. Now that you've taken note, forget it. An experience,.. I have annoyed one of our domineering Australian politicians who has a speech impediment and uses ineffective exercises even on the floor of the house. I pointed out to him (via Twitter) that he could become far and away an even better performer than his leader by saying the word "regularly"with all its component parts . The change was magic. Purely from ensuring tongue mobility and that it contacted the alveola ridge. Such activity may seem rude to you but Australians are devestatingly direct. IMO reading is your best education, reading from good reliable technical authors. I am a real fan of the marvelous A.C. Grayling. His Ideas that Matter is an excellent book. I admit to getting a tiny bit impatient with his puncuation at times and even his run on sentences yet it becomes obvious that he has carefully condidered his choices. There is even the odd abreviated section where I reach the end and mutter to myself, "I didn't understand a word of that." Another is to keep your cell phone handy for the assistance of Cortana to discover the meaning of certain of AC's words. He only uses these marvelous words to avoid writing pages of -stuff- always on guard against being directed to Americanish of course. I hope you glean something from that, it's 4.30am and cold here in July. .-)