"People suddenly change their mind about you without a good reason."

I don't understand how a person can change so suddenly.

He is talking about something and suddenly changes the subject.

It almost seemed as if summer had suddenly changed to the middle of fall.

There was a reason why the world had suddenly changed.

It changed suddenly to present a face once again, this time a woman's.

"What if he gets free and suddenly changes his taste in music!"

Near the end of the period, the weather changed suddenly.

As the game suddenly changed, we could see what was happening.

As they passed under it the whole scene suddenly changed.