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It [may|ought] sound silly to some, but I have a great fear of flying. My family has moved to Australia, so I [can|should] only fly there whenever I want to visit them! My friends keep telling me that I [don't need|shouldn't] worry so much, because all planes [may|must] go through a safety inspection before they take off. My problem is that whenever I'm nervous I [need to|can] move around, and I simply [can't|needn't] do that on a plane, it's not allowed!