Consider the following premises. Patricia is drinking water if and only if Barbara is taking a plane. Patricia is drinking water if and only if David is a lawyer. For all x_10, x_10 will not take a plane. Can we infer the following from them? David is a lawyer.
 From the fact that for all x_10, x_10 will not take a plane we can infer that Barbara is not taking a plane. From the fact that Patricia is drinking water if and only if Barbara is taking a plane, and that Barbara is not taking a plane we can infer that Patricia is not drinking water. Finally, from the fact that Patricia is drinking water if and only if David is a lawyer, and that Patricia is not drinking water we can infer that David is not a lawyer, which contradicts that David is a lawyer. Therefore, the answer is no.