Preterite / Imperfect

http://mld.ursinus.edu/~jarana/Ejercicios/self-check/pret_imp1.html

http://www.123teachme.com/learn_spanish/node/1769

http://legacy.lclark.edu/~benenati/pretimp/preterito1.html

http://legacy.lclark.edu/~benenati/pretimp/preterito2.html

http://legacy.lclark.edu/~benenati/pretimp/imperfecto1.html

http://legacy.lclark.edu/~benenati/pretimp/imperfecto2.html

http://legacy.lclark.edu/~benenati/pretimp/impret.html

http://legacy.lclark.edu/~benenati/pretimp/primp.html