Answer:
Some examples of informal and formal nouns are:
ask is informal, vs. enquire which is formal
informal/formal
ask for/request
tough/difficult
cheap/inexpensive
dare/challenge
makeup/fabricate
Step-by-step explanation:
Informal words shouldn't b used with teachers**
formal words are just classier versions of words. You wouldn't say what's up in an email (well maybe), but you should say hello