shall, must, should Shall-Used to indicate a future action. I have seen a translation as "it shall be"---deberá. Must-Indicating that something needs to be done. I think it is translated as deber. I must finish my homework. Should-Used to indicate obligation. It is like "must" but it is not as strong as "must" I should do my chores. I must stop the dictator. I shall become president someday.