What is control segment in GPS?

Represent the union of two sets by Venn diagram for each of the following.

$X=\{x | x$ is a prime number between $80$ and $100\}$

$Y=\{y | y$ is an odd number between $90$ and $100\}$

Television and mobile phones are wonderful modern inventions. They are very useful too. However, spending too much time watching television or using mobile phone can also have harmful effects.

Do you know how these two things can harm you?