From “The Second Coming” by William Butler Yeats

Question

The darkness drops again; but now I know
That twenty centuries of stony sleep
Were vexed to nightmare by a rocking cradle. . . .

In these lines from “The Second Coming” by William Butler Yeats, a noun clause serves as a direct object. What is the introductory word that signals the noun clause?

Fill in the blank text field 1

Answer 1

that