True or false : Cubic functions are odd functions.

Complete:

_____________ functions symmetric to the y-axis.

Is $f(x)=x$ even or odd function?

Is $f(x)=x+\sin x$  even or odd function?

Is the sentence true or false?

The sum of two even functions is even function.

Is $f(x)=3\sin x$ even or odd function?

Is $f(x)=x^5$ even or odd function?

Is $f(x)$ $=$ $2$ $x^3$  even or odd function?

Complete:

_____________ functions symmetric on the origin.

True or false: The sum of an even and odd function is neither even nor odd function.