If you have 33 minutes free to study English, why not watch this webinar on formal and informal English?
A webinar is a web-seminar, so it’s like a discussion lesson via the internet. You can take part in webinars live and can interact with the speaker. This one is the recorded version though. There is so much great information in it, and formality is key to using English well.
You can also download the text from the webpage so you can read what is said too.
Make some time to watch it, and let me know what you think.