9. (10 points) Using four 4s and some addition, subtraction, multiplication, division signs, and parentheses, write four expressions that equal $3$, $4$, $5$, and $6$ respectively.
【Analysis】Since $12 \div 4=3,4+4+4=12$, it can be written as $(4+4+4) \div 4=3$; since $4 \times(4-4)=0,4-0=4$, it can be written as $4-(4-4) \times 4=4$; since $4 \times 5=20,20 \div 4=5$, it can be written as $(4 \times 4+4) \div 4=5$; since $2+4=6,(4+4) \div 4=2$, it can be written as $(4+4) \div 4+4=6$.

【Solution】Solution: $(4+4+4) \div 4=3$;
4 - $(4-4) \times 4=4$;
$(4 \times 4+4) \div 4=5$;
$(4+4) \div 4+4=6$;