掌握重点词汇
单词：survey conduct percentage disadvantage alien discussion skim scan atmosphere carbon dioxide moon mile
词组2. so far away from Earth 离地球如此之远
3. start with a discussion 以讨论开始
begin/start with sth. 以------开始
end with sth. 以-------结束
4. the situation on Earth 地球上的状况
5. do harm to…=be harmful to…对------有害
6. have robots do 让机器人做某事
have/make/ let sb do 让某人做某事
