单词拼写。 根据下列各句句意和空白后的汉语提示词，在相应的横线上写出对应单词的正确形式， 每空只写一词。 1. Twenty years after the event, his death still remains a _____ (谜团). 2. Xi'an is a famous city with well-preserved _____ (古代的) city walls. 3. My husband took the full _____ (责任) for organizing the trip for my family. 4. Jimmy's grandmother always _____ (宠坏) him with toys and candies. 5. I kept contact with my three-year-old boy _____ (频繁地) when I was in America. 6. The students _____ (响应) to my suggestion very quickly and take actions immediately. 7. Never will I _____ (原谅) him for what he does to my sister. 8. You can adjust the _____ (高度) of the chair conveniently. 9. _____ (九十) plus ten is one hundred. 10. Have you ever _____ (梦想) of playing in front of thousands of people at a concert?