一、单词拼写：
根据下列句子及所给汉字注释，在句子右边的横线上，写出空缺处单词的正确形式。（每空只写一词）
1. Chinese history is filled with great _______(成就) in science and technology. 1.____________
2 . I’d like to write him a letter, but I don’t know his _______(地址). 2. ____________
3. At that time in the southern states, blacks were not treated as equal __________(公民) in the USA. 3.___________
