These two prefixes are commonly used to make opposites from adjectives. Here you have some links to practice this grammar topic:
Lost of funny activities and games to improve your English on SchoolExpress website
Word Drop is a very funny Tetris game to test your vocabulary.
Here you have some resources to practice countries and nationalities in English:
Here you have a bit of informacion about numbers.
How to write numbers
Enter a number and this script will write it out in plain English. Your number can be up to 303 digits long.