Not 100% certain whether you are asking for a question or asking a question about using the passive voice. "He...is often laughed at," is already passive. In the active voice it would be, "People often laugh at him." "He is often foolish," is subject + verb + adverb + adjective and so cannot be transformed into the passive. However, if we wish to switch focus in the sentence, we can move the position of the adverb: "Often, he is laughed at." To form a question, "Is he often very foolish and laughed at?"