What are the "Boosters"?

Question

The FAQ mentions "Boosters" in its section about the streak feature: https://www.sololearn.com/faq#q60

What are these Boosters?

Answer 1

Евгений Booster is extra practice. In JavaScript and Python Intro course you will get boosters but it will be invisible untill you reach them. Only for quiz questions.

Answer 2

Yes in new course

Answer 3

Yes you need pro membership.
May be you will get atleast one booster for practice.

Answer 4

R❇️🇮🇳 Do you mean the new ones?

Answer 5

R❇️🇮🇳 Do I need to have a Pro subscription to see and use them?