Complete the sentences with the suitable infinitives: to understand, to fly, to read, to know, to buy, to see. this is the book for she will be the last person __ the truth. the old lady is difficult

This is the book for you to read.
She will be the last person to know the truth.
The old lady is difficult to understand.

This is the book for you to read.
She will be the last person to know the truth.The old lady is difficult to understand.