Consider the following premises. For all x_10, x_10 is a mechanic or x_10 will not sleep. For all x_10, if x_10 were a cashier, then x_10 is sleeping. For all x_10, x_10 will drink water if and only if x_10 is a mechanic. For all x_10, x_10 is a cashier or x_10 will drink water. Can we infer the following from them? There is at least one x_10 for which x_10 is not a mechanic.
 From the fact that for all x_10, x_10 is a mechanic or x_10 will not sleep we can infer that for all x_10, if x_10 sleeps, then x_10 is a mechanic. From the fact that for all x_10, x_10 will drink water if and only if x_10 is a mechanic we can infer that for all x_10, if x_10 drinks water, then x_10 is a mechanic. From the fact that for all x_10, if x_10 were a cashier, then x_10 is sleeping, and that for all x_10, if x_10 sleeps, then x_10 is a mechanic we can infer that for all x_10, if x_10 were a cashier, then x_10 is a mechanic. Finally, from the fact that for all x_10, if x_10 were a cashier, then x_10 is a mechanic, that for all x_10, if x_10 drinks water, then x_10 is a mechanic, and that for all x_10, x_10 is a cashier or x_10 will drink water we can infer that for all x_10, x_10 is a mechanic, which contradicts that There is at least one x_10 for which x_10 is not a mechanic. Therefore, the answer is no.