List all the elements of the following sers :

$D = \{ x:x$ is a letter in the word $"\mathrm{LOYAL}" $ $\} $

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

$\{ x:x$ is an equilateral triangle in a plane $\}  \ldots \{ x:x$ is a triangle in the same plane $\} $

Examine whether the following statements are true or false :

$\{ a\}  \in \{ a,b,c\} $

State whether each of the following set is finite or infinite :

The set of animals living on the earth

Examine whether the following statements are true or false :

$\{a\} \subset\{a, b, c\}$

Consider the sets

$\phi, A=\{1,3\}, B=\{1,5,9\}, C=\{1,3,5,7,9\}$

Insert the symbol $\subset$ or $ \not\subset $ between each of the following pair of sets:

$A \ldots C$