Siltstones
(siltstone 的复数) n.[地]粉砂岩
🗣️ 情景例句
You have lots of time to decide.
你有很多时间做决定。
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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。