Consider the following premises. For all x_9, if x_9 writes a letter, then x_9 is curious. For all x_9, x_9 is fast or x_9 will write a letter. For all x_9, if x_9 were fast, then x_9 is curious. For all x_9, x_9 is sad. There is at least one x_9 for which if x_9 makes tea, then x_9 is not curious. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_9 for which if x_9 makes tea, then x_9 is not curious.
That is one of the premises. Therefore, the answer is yes.