$A$ part of a line with one end point is called a $\ldots \ldots \ldots .$

An angle whose measure is $90^{\circ}$ is called a $\ldots \ldots \ldots$

In the figure,ray $OS$ stands on a line $POQ$. Ray $OR$ and ray $OT$ are angle bisectors of $\angle POS$ and $\angle SOQ$,respectively. If $\angle POS = x$,find $\angle ROT$. (in $^o$)

In the figure,if $x+y=w+z$,then prove that $AOB$ is a line.

$A$ part [or portion] of a line with two end points is called a $\ldots \ldots \ldots$

In the figure,lines $AB$ and $CD$ intersect at $O$. If $\angle AOC + \angle BOE = 70^o$ and $\angle BOD = 40^o$,find $\angle BOE$ and reflex $\angle COE$.