4.) Given C(x,y) mean that person x has chatted with person y. Express the statement "There is a student in this class who has chatted with exactly one other student using quantifiers.

5.) Given E(x,y) mean that person x has sent e-mail to person y. Express the statement "No student in this class has sent email to exactly two other students in this class" using quantifiers.

6.) Let Q(x,y) be the predicate that x has taken y, where x ranges over students in this class and y ranges over math classes at this school. Express the statement "Every student in this class has taken exactly two math classes at this school" using quantifiers. Then, form the negation of the statement so that no negation is to the left of the quantifier. Express the negation in simple english.