Does Jim come from the USA or Australia? 关于句中冠词,为何USA前加the 而

Does Jim come from the USA or Australia? 关于句中冠词,为何USA前加the 而 Do you come from the USA?No,l___from Australia. they come from the USA,对the USA 提问 boy （） Jim is from the USA Our English teachers come from the USA改为否定句 Do you come from the USA?改为同义句 I'm from USA .USA前面要加the Does Jack come from the USA? No,he comes from E_____. Where does Mark Twain come from?A.The UK B.The USA C.Canada Does the come from Australia?改成同义句 USA前一定要加the吗 I'm from the USA 同义句