Косвенная речьMary says: "I am am school every Saturday".Nick asks:"Did you visit Granny?"

Mary says: \"I am at school every Saturday\". —Mary says that she is at school every day.

Nick asks:\"Did you visit Granny?\" — Nick asks if I visited Granny.

If the first part is in Present we don’t change tense in the second part.

The first part Mary says, Nick asks — Present Indefinite.  

In these sentences only  pronouns are changed, I — she, you — I.

In the first sentence we add or don’t add that.

The second sentence is interrogative and it hasn’t an interrogative word, so we add if.