'Happen' in the Bible

They were on the way, going up to Jerusalem; and Jesus was going in front of them, and they were amazed; and those who followed were afraid. He again took the twelve, and began to tell them the things that were going to happen to him.

"When you hear of wars and rumors of wars, don't be troubled. For those must happen, but the end is not yet.

Most certainly I say to you, this generation will not pass away until all these things happen.