科研之友
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摘要
<正>A student is sitting at an astronomy(天文学) lecture in college,when the professor mentions,"In about 15 billion years,the sun will burn out and all life on earth will cease to exist.""Excuse me,professor,did you say 5 billion years or 15 billion?""15 billion.""Whew,thanks,because I was really getting worried."
- 出版日期2020
