动词make sth sth,使……成为……,这句话的含义是“使曾经不可能的技术成为现实”。空格处用what引导宾语从句,代替Advances in science and technology,what在从句what seemed impossible中做主语。
句意:每个人都知道,月亮每月绕地球转一圈。考查非限制性定语从句。非限定性定语从句,对整句表示说明时,通常用as,如as we all know, as it is known, as is known to all, as it is, as is said above, as always mentioned above, as is usual, as is often the case, as is reported in the newspaper等句式。