[练习题]Fill in the blanks with one of the items given.solve, solved, solving；all, either, whole The past is filled with incredible mysteries. The clues to them are around, hidden in plain sight.
正确答案：solving；all
题目解析
本题考查动名词和固定搭配。句中的 clues to 后跟名词，不跟动词，故第一个空处应用动名词形式；all around 是固定搭配，表示“在周围，到处”。
them are 