Answer:
The correct answers are:
1) Let’s catch some grub before kickoff (very informal)
2) It is imperative to develop cognitive skills at an early age. (formal)
3) I like to eat dessert before the meal. (informal)
4) My older sister makes delicious pizzas! (informal)
5) This silly girl is seriously ticking me off. (very informal)
6) The process of becoming adequately fit to join the army requires arduous training.
Step-by-step explanation:
Formal language: formal language is generally used in writing, uses complex grammar structures ,and specific and more specialized vocabulary. In the sentences provided some examples are of formal vocabulary are: imperative, conginitive, adequately, arduous, process.
Informal language: informal language is generally used in speaking and in every day language. Grammar expressions are shorter and the vocabulary used is more simple in informal language.
Very informal language: it is commonly used with contractions, use of pronouns and idiomatic expressions that denote informality as in "catch some grub before kickoff", "This silly girl is seriously ticking me off".