1.an amount of something that you are officially allowed by a particular set of rules or by the law.
2.pieces of paper containing official information.
3.to tell customs officers (= at the border of a country) that you are carrying goods on which you should pay tax.
4.complete, correct, and legal
5.to be present at an event or activity.
6.to take part in something.
7.to put a mark on something using ink and a stamp
8.the people whose job is to look after the passengers and serve their meals.
9.to give things to a large number of people