Do you know anything about airport security(安全)? In order to protect passengers, airports have ________rules. Some of these rules include:
Restricted items
________ are not allowed on board. In the past, knives under four inches were allowed on board, ________ now, knives are not permitted at all.
ID checks
All passengers must have ID cards ________ match their boarding passes. Passengers are unable to fly_________these documents.
Security on the aircraft
Generally, ________ are not permitted to enter the cockpit, where the pilot sits, ________when the plane is in the air. In order to increase security, bullet-proof doors and locks are now standard on all planes.
Forbidden liquids
No liquids over 100ml may be ________ on board in hand luggage. Liquids ______ 100ml must be carried in a clear plastic bag. This ________water, shampoo, toner etc