I cant open this lock,there must be ____key that will open it.填哪个_英语解答

I cant open this lock,there must be ____key that will open it.
填哪个词?
some/any/every/each/either
说明理由

人气：187 ℃　时间：2020-02-05 20:22:32

解答

some
some + 名词单数,表示这类物品中的某一个,但具体哪一个不知道