'Certain' in the Bible

Now there was a certain man of Ramathaim, a Zuphite of the hill-country of Ephraim, named Elkanah; he was the son of Jeroham, the son of Elihu, the son of Tohu, the son of Zuph, an Ephraimite:

If it goes by the land of Israel to Beth-shemesh, then this great evil is his work; but if not, then we may be certain that the evil was not his doing, but was the working of chance.

But certain good-for-nothing persons said, How is this man to be our saviour? And having no respect for him, they gave him no offering.

And the men of Israel said, Have you seen this man? Clearly he has come out to put shame on Israel: and it is certain that if any man overcomes him, the king will give that man great wealth, and will give him his daughter, and make his father's family free in Israel.

And David said to Ahimelech the priest, The king has given me orders and has said to me, Say nothing to anyone about the business on which I am sending you and the orders I have given you: and a certain place has been fixed to which the young men are to go.

Now a certain man of the servants of Saul was there that day, kept back before the Lord; his name was Doeg, an Edomite, the strongest of Saul's runners.

And David said to Abiathar, I was certain that day, when Doeg the Edomite was there, that he would take the news to Saul: I am responsible for the lives of all your father's family.

And said to him, Have no fear, for Saul my father will not get you into his power; and you will be king of Israel, and I will be by your side, and my father Saul is certain of this.

So take care to get knowledge of all the secret places where he is taking cover, and be certain to come back to me, and I will go with you: and without doubt, if he is anywhere in the land, I will get him, among all the families of Judah.

And now I am certain that you will be king, and that the kingdom of Israel will be made strong under your authority.