'Whether' in the Bible

“So be alert [give strict attention, be cautious and active in faith], for you do not know which day [whether near or far] your Lord is coming.

But understand this: If the head of the house had known what time of the night the thief was coming, he would have been on the alert and would not have allowed his house to be broken into.

But Jesus kept silent. And the high priest said to Him, “I call on You to swear a binding oath by the living God, that you tell us whether You are the Christ, the Son of God.”

But the rest said, “Let us see whether Elijah will come to save Him [from death].”