SESSION 1 ANSWER:
its trying to say that when you post something online, it is definately public and not private so its saying to think about the consequences before posting something online.. and what happened to Sarah is one of the consequences because apparently she posted some nude photos of herself online and now everyone knows that she did it and can see those nude photos of her.
SESSION 2 ANSWER:
no, he should not open the file attatchment because even though the fact that there are cases in that place is true, it doesn't mean that the medicine that his friend recommended is effective. and the file attatchment might be a virus. and if he received the email from a familiar email he may know of, he should call his friend and verify that he sent the email and that the medicine is real too.
