Predicate Logic questions

The next two short$-$answer questions $($Questions $2,3)$ are about Predicate Logic.

Suppose that:

$$ variables X$,$Y can represent any device,

$$ the predicate simulates$($XY$)$ is True if and only if device X simulates device Y$.$

$$ simulates $($X$,$X is always True

In each of the next two questions, express the given sentence in predicate logic.

The following symbols are provided for you to copy if you wish $($though not many of them are useful in this question$)$: a$)$ Some device can simulate every device.

This one must be written as an existential statement $($starting $3..)$ b$)$ Not all pairs of devices can simulate each other.

This one must be written as an existential statement $($starting $3..)$