At last, but not the least.
Here is an exercise with modal verbs.

Nota: o "might" é um modal verb que também pede permissão.Se tiveres dúvidas é só postares ou perguntares na aula, OK?

http://perso.wanadoo.es/autoenglish/gr.may2.i.htm

More exercises to practise

Here are three different exercises for you to revise somethings you've already learned.

http://www.englishexercises.org/makeagame/viewgame.asp?id=3609
(Occupations)

http://www.englishexercises.org/makeagame/viewgame.asp?id=3607
(Travel)

http://www.englishexercises.org/makeagame/viewgame.asp?id=3612
(Numerals)

Irregular verbs

Practice the Irregular Verbs

http://www.englishlearner.com/tests/irregular_past_verbs_matching_1.shtml