Possible Duplicate: Should I say 'What I wanted to say is' or 'What I wanted to say was'? Which one is correct: Introduce additional user interface widget so that it was ...
They knew what mercy is. They knew what mercy was. Mercy is something that always exists so can I say is as in the above example?
Following Martha's advice I am splitting up a question Compound sentences, the punctuation and mooore. Let's put what I said / wrote something in the past. And now I want to elaborate some key points ...