1 . It may seem like building ________(n. 城堡) in the air(幻想), but given the rate at which artificial intelligence, or AI, is being developed, in the future such dreams may actually come true.(根据汉语提示单词拼写)

2 . The ancient c________ were made of earth and wood, and they were likely to suffer attacks by fire.(根据首字母单词拼写)

3 . With a local villager guiding us, we finally found the ancient _____________(城堡).(根据汉语提示单词拼写)