logical deduction – A query from a nigh-omnipotent god

Set-up:

John and Bob are enjoying a recreation that goes like this:

1. Bob chooses a query, although some kinds of questions are off-limits, which can be listed. After doing this, he can not do the rest till the sport is over.
2. John reads the query. Between step 1 and a pair of, he might do no matter he needs, besides trigger Bob’s dying in every other manner than doubtlessly making his reply incorrect.
3. John asks Bob the query Bob himself formulated.
4. Bob solutions the query to one of the best of his skill. If Bob is appropriate on the time of answering, John won’t ever kill Bob. If he’s improper on the time of answering, John will shoot him lifeless.

So, what questions are off-limits?

1. The query can not have a paradoxical reply. So, for instance, Bob’s not allowed to decide on the query “Is that this sentence false?”
2. The query can’t be relating to a truth outdoors of John’s bodily energy to alter, or relating to a truth John is disallowed by the sport to alter. So, he cannot select e.g. “What’s 2 + 2”, or “What did you eat yesterday?”
3. The query can not seek advice from the longer term.

There’s an omniscient field there to inform them if John is bodily unable to alter a truth or not. If he’s bodily unable, Bob should ask a brand new query. John and Bob are common males.

The puzzle:

What query can Bob select such that he ensures that John doesn’t shoot him lifeless?