*****NOT A TEACHER *****
Here in the United States of America, everyone who goes to the airport is subject to a screening (to prevent terrorists from
getting on the airplane). In other words, they may or may not screen (check) you with a machine or even with their hands!
Not everyone is subjected to a screening. For example, the government is starting a new program. If it thinks that you are
definitely a good guy, you can get permission to board an airplane without a screening. BUT even those people will still be
subject to a screening if one of the government screeners suspects you of being a bad guy.
In other words, when you read that people are subject to something, it means that it may happen or it may not happen.
When you read that people were subjected (the passive), it means that it happened. For example, at this very moment
people in country X (I am not permitted to name the country) are being subjected to horrific violence on the part of their
country's army.