Consider the following premises. Barbara is sad. For all x_3, x_3 will make tea. Can we infer the following from them? There is at least one x_3 for which x_3 will make tea.
 From the fact that Barbara is sad we can infer that there is at least one x_3 for which x_3 is sad. From the fact that there is at least one x_3 for which x_3 is sad, and that for all x_3, x_3 will make tea we can infer that there is at least one x_3 for which x_3 is sad and x_3 will make tea. Finally, from the fact that there is at least one x_3 for which x_3 is sad and x_3 will make tea we can infer that there is at least one x_3 for which x_3 will make tea. Therefore, the answer is yes.