dear
The Italian word 'caro' can be used to express a sense of affection or endearment, similar to the English word 'dear'. It can be used to address someone in a loving or familiar manner, as in 'Caro amico' (Dear friend). However, it can also be used to express a high price or cost, as in 'Questo libro è molto caro' (This book is very expensive).
Dear Mario, how are you?
This denotes a salutation in a letter. 'Caro' is used to address someone in a friendly or familial manner, similar to 'dear' in English.
The rice is very expensive
This is used to express the cost of something. 'Caro' in this context means 'expensive'.
You are dear to me
This expresses affection or sentiment towards someone. 'Caro' in this context means 'dear'.