Make correct statements by filling in the symbols $\subset$ or $ \not\subset $ in the blank spaces:

$\{ x:x$ is a circlein the plane $\}  \ldots \{ x:x$ is a circle in thesame plane with radius $1$ unit $\} $

List all the elements of the following sers :

$C = \{ x:x$ is an integer ${\rm{; }}{x^2} \le 4\} $

Write the following sets in roster form :

$D = \{ x:x$ is a prime number which is divisor of $60\} $

Write the following intervals in set-builder form :

$\left( { - 3,0} \right)$

In each of the following, determine whether the statement is true or false. If it is true, prove it. If it is false, give an example.

If $A \subset B$ and $B \in C,$ then $A \in C$

Which of the following are sets ? Justify your answer.

The collection of all boys in your class.