It was obvious to tell a crook from a regular person
It's obvious that you don't know how to use the word obvious in a sentence because you asked a question on how to use it.
This seems to have an obvious answer. The answer was obvious to all present.
I think it's rather obvious. The obvious solution is the simplest, in this case.
It was obvious by her build that she was a weightlifter.
I came to the obvious conclusion to use answers.com to get this sentence
the danger was obvious
The answer to your question is so obvious that the v is not even required! ;)
It was obvious to everyone in the room that she was in turmoil during the quiz.
His avariciousness was obvious as he greedily grabbed all the available food.
Machismo is an exaggerated sense of masculinity. An example sentence would be: It was very obvious that he was feeling very machismo.
His obvious contrivance was just another thin plot.
The truth was evident ("in plainview", "obvious", logical)