Present Simple/Present continuous and Past simple/Past continuous

For the students in 2nd course of secondary education, or for the ones who are in 3rd, and want to remember the grammar strucutures of this first term, here you are:
Present Simple: http://www.isabelperez.com/happy/tenses/present_simple.htm
Present Continuous: http://www.isabelperez.com/happy/tenses/present_cont.htm
Past Simple: http://www.isabelperez.com/happy/tenses/past_simple.htm
Past Continuous: http://www.isabelperez.com/happy/tenses/past_cont.htm

and for these last students ( in 3rd course), more verbal tenses: Present Perfect  http://www.isabelperez.com/happy/tenses/pres_perfect.htm