Consider the following premises. For all x_1, x_1 will work. For all x_10, x_10 is a janitor. Can we infer the following from them? For all x_1, either x_1 is a janitor or x_1 will work are not true.
 From the fact that for all x_10, x_10 is a janitor we can infer that David is a janitor. From the fact that David is a janitor we can infer that there is at least one x_1 for which x_1 is a janitor. Finally, from the fact that there is at least one x_1 for which x_1 is a janitor, and that for all x_1, x_1 will work we can infer that some janitors will work, which contradicts that For all x_1, either x_1 is a janitor or x_1 will work are not true. Therefore, the answer is no.