GRAMMAR
1. https://personal.colby.edu/~bknelson/SLC/
2. https://www.linguasorb.com/spanish/verbs/most-common-verbs/
3. https://conjuguemos.com/index.php
4. http://www.spanishgrammarguide.com/
5. http://100spanishverbs.com/
6. http://www.spanishconjugator.com/http://laspreposiciones.com/por-and-para.html
PRONUNCIATION
1. https://www.123teachme.com/learn_spanish/alphabet_pronunciation_2
2. http://100spanishwords.com/
LISTENING
1. http://www.laits.utexas.edu/spe/
2. http://www.cuentosparachicos.com/ESP/audiocuentos/