Classes
n. 级别, 阶级（class复数形式）
🗣️ 情景例句
Then. How can you prove yourself?
你怎么来证明你自己呢？
I hope he will meet me at the airport.
我希望他能到机场接我。
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。