Radio communication（）for many years and helps to save tens of thousands of lives. ["has been used","have been used","has used","have used"]
防火堤和隔堤设计应符合哪些规定？
きのうは（）一日でした。 ["楽しい","楽","楽しいかった","楽しかった"]
All coast radio stations（）DSC installed for VHF and HF. ["have","had","are having","have had"]
丝绸之路在中国境外的咽喉地带是（）。 ["阿富汗","伊朗","伊拉克","印度"]
液化烃储罐成组布置时，应符合哪些防火规定？其防火堤如何设置？
