1. What is the goal of the text? 2. What is the definition of helicopter according to the text? 3. how does a helicopter produce thrust? 4. what are the advantages of helicopter for civilian? 5. what are the advantages of helicopter as military aircraft?
the answer nomber 4 and 5 can't answer it, because, the text is incomplete. i answer it based on the text that u post here, thx and good luck!