Hi, When we are caught by others while we are doing something we should not do, we say that we are "caught in the act" When we suddenly realise that we are doing something, we say that we "catch ourselves in the act". Perhaps your teacher wants you to be mindful of your use of those words in daily life. Hope this helps. Cheers, Lance

Phrase is a small group of words. Words when used together become a phrase and it gives a specific meaning.