In this task, given a sentence in the English language, your task is to convert it into English Tokens.

A gene has been discovered that turns stem cells into cancer killers, promising new treatments that boost the body's ability to destroy tumors.
A gene has been discovered that turns stem cells into cancer killers , promising new treatments that boost the body 's ability to destroy tumors .

Ferrari's second driver, Rubens Barrichello, announced today that he will depart from Ferrari at the end of the season.
Ferrari 's second driver , Rubens Barrichello , announced today that he will depart from Ferrari at the end of the season .

The tiger was shot dead by police who were called to the scene.

The tiger was shot dead by police who were called to the scene .