Discover ambiguities or omissions in the following statement of requirements for part of a ticket-issuing system:
An automated ticket machine sells rail tickets.
Users select their destination and input a credit card and a personal identification number.
The rail ticket is issued and their credit card account charged.
When the user presses the start button, a menu display of potential

Before they can be published, scientific papers must be peer-reviewed. this means that: a) some other scientific experts read the papers and guarantee that they are true.b) some other scientific experts read the papers and provide quality control by eliminating many mistakes.c) an editor reads the papers, to make sure that all the semicolons are in the correct places.d) everyone in the world is given the opportunity to comment on the papers through a specially maintainedblog.e) government bureaucrats read the papers, to be sure that the papers do not insult the political positions ofthe current officeholders.