Fill in the blanks to make each of the following a true statement:
$A \cup A^{\prime} = \ldots$

If $A = \{x : x \text{ is a multiple of } 3\}$ and $B = \{x : x \text{ is a multiple of } 5\}$,then $A - B$ is equal to,(where $\bar{B}$ is the complement of set $B$.)

Let $U$ be the set of all triangles in a plane. If $A$ is the set of all triangles with at least one angle different from $60^{\circ},$ what is $A^{\prime}$?

Taking the set of natural numbers as the universal set,write down the complement of the following set:
$A = \{ x : x \text{ is a positive multiple of } 3 \}$

Taking the set of natural numbers as the universal set,write down the complement of the following set:
$A = \{ x : x \text{ is an even natural number} \}$

Let $U = \{1, 2, 3, 4, 5, 6, 7, 8, 9\}$,$A = \{1, 2, 3, 4\}$,$B = \{2, 4, 6, 8\}$,and $C = \{3, 4, 5, 6\}$. Find $(B - C)'$.