A．The man had placed them in their car.
B．The man had forgotten to bring them.
C．The woman had lent them to the hotel owner.
D．The woman had left them next to the picnic table.

A．They should help maintain the equipment.
B．They should teach their children how to use the equipment.
C．They should stop their children from climbing ladders.
D．They should keep a watchful eye on their children.