Viet Nam / reported / the / Thien Duong / it is / longest cave / in / that / is /27/30Viet Nam / reported / the / Thien Duong / it is / longest cave / in / that / is /It is reported that Thien Duong is in Viet Nam the longest cave It is reported that Viet Nam is the longest cave in Thien Duong It is reported that is the longest Thien Duong cave in Viet NamIt is reported that Thien Duong is the longest cave in Viet NamGiải thíchĐáp án đúng là D