Blackboard model
[计] 黑板模型
🧩 词语组成解析
🗣️ 情景例句
In about 30 minutes.
大约半小时后。
Sometimes gain is to lose.
有时得即是失。
But here we come up against the most difficult of all obstacles to contact with people on other planets ----the astronomical distances which separate us.
然而，在和外星人联系中我们遇到的最大困难是分隔我们的天文距离。