UNIT 8

Click here and you will find some interesting grammar exercises
http://www.oup.com/elt/global/products/englishfile/elementary/a_grammar/file05/
http://www.oup.com/elt/global/products/englishfile/elementary/a_grammar/file06/
http://www.oup.com/elt/global/products/englishfile/elementary/a_grammar/file07/
http://www.isabelperez.com/grammar.htm#Grammar