When Should I use conjunction and implication? (Logic)

Question

I'm confused when I try to "translate" from a situation in natural language to a logic proposition, particularly with the implication ($A \implies B$) and conjunction ($A \land B$):

For example:

$E(x)$ = "$x$ is a student"

$P(x)$ = "$x$ is a teacher"

$Q(x,y)$ ="$x$ has been student of y"

$R(x,y)$ = "$x$ has asked a question to y"

And the situation: "All students have asked a question to some teacher of which haven't been his students"

I tried : $\forall x \exists y[E(x) \wedge P(y) \wedge \lnot Q(x,y) \wedge R(x,y)]$, Is it correct?

If you can tell me a way to choose between implication and conjunction it would be great, thank you very much

Answer 1

$\forall x \exists y((E(x) \land P(y) \implies (R(x,y) \land \lnot Q(x,y))$

The reason why I choose the implies here is to show that if $x$ is a student and $y$ is a teacher then our right side of the implication is as follows.

Answer 2

$\forall E(x)\exists P(y), R(x,y)\implies \sim Q(x,y)$