It has been proved that is irrational. Ultimately, however, the tactic proved ineffective and was abandoned. However, these negotiations ultimately proved fruitless. It proved unsuccessful and was abandoned. Straightforward as the investment seemed, it proved otherwise. However, the task has proved daunting. This, however, proved impossible for him. However, the claims later proved to be false. They proved unpopular, however, and were withdrawn later. However, this proved to be false. However, profits proved to be elusive. This, however, proved a costly failure. The numbers, however, proved insufficient. His successes, however, proved ephemeral. Unfortunately, this proved to be false.