Chertoff said he has no immediate plans to raise the overall threat level in the United States, which is at yellow, signifying an elevated level.是什么意思_Chertoff said he has no immediate plans to raise the overall threat level in the United States, which is at yellow, signifying an elevated level.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句