Question

【题目】Neil Armstrong is the first man to walk on the Moon. It was brave of him to go to a place that was (know) to people at that time.

Answer 1

【答案】unknown
【解析】句意：句意：尼尔·阿姆斯特朗是第一位在月球上步行的人。他那时去一个不为人知的地方很勇敢。在第一次登月之前，月球对人类很陌生，人们对它不知道，故填：unknown。