Consider the following premises. There is at least one x_5 for which if x_5 were curious, then x_5 is playing squash. For all x_5, x_5 will play squash if and only if x_5 is curious. Can we infer the following from them? For all x_5, x_5 will play squash if and only if x_5 is curious.
That is one of the premises. Therefore, the answer is yes.