The correct answers are The dinosaur bones must not be touched by anyone and Flash photography cannot be used in the bat cave.

To form the passive voice with modal verbs, we use modal + be + past participle (e.g., must be touched, cannot be used).

"The historical paintings should not touch by visitors" is incorrect because it is missing the verb "be" and uses the active verb "touch" instead of the past participle "touched."

"Food and drinks must left at the entrance" is incorrect because it is missing the verb "be" (must be left).