⏪ 新概念英语 - [4-035] - (97版) ⏩ ⏳ 正在检测本地文件... First listen and then answer the following question.先听录音，然后回答后面的问题。When will it be possible for us to think seriously about colonising Mars? 我们什么时候才能认真考虑殖民火星？Space odyssey 📁 请先导入本地文件， 需要帮助？点击我 ↗