Formal and informal language serve different purposes. The tone, the choice of words and the way the words are put together vary between the two styles. Formal language is less personal than informal language. Informal language is more casual and spontaneous. It is used when communicating with friends or family either in writing or in conversation. As if there wasn’t already enough to learn when someone is trying to master the art of speaking English, an informal language all of its own exists within this tricky tongue. This is the language of English slang: the words that aren’t usually taught within formal English courses, but that everybody will hear all around when people are conversing with native speakers.
Read the next statements.
1^st) Have you tried this ice cream? It's the bee's knees, it really is! 2^nd) I love “The Big Bang Theory”. The characters are so geek! 3^rd) You spend far too much time watching the telly. 4^th) Someone nicked my bike, bro! 5 th) Make us a cuppa, will you, love? 
Tick the correct alternative.