No, I have never experienced that fear.

It has never occurred to me to be afraid of that, but now that you mention it, it seems scary and/or I can relate to that fear.

Only when I have been in a situation where it was probable that it would happen in the near future.

I used to be afraid of this but not any more.

Yes, I have experienced this fear but it was an anomaly.

Yes, this is a reoccurring fear.