Then xnyn and xn/yn may or may not be limited.
Such as xn = 1/n, yn = n,
Then xnyn and xn/yn have limits,
Another example is xn = 1, yn = (- 1)? ,
Xnyn and xn/yn are not limited.
But yn/xn must have no limit, because if there is a limit, then xn * (yn/xn) = yn also has a limit, which obviously does not meet the conditions.