孩子们值得拥有挑战他们的书，而不仅仅是娱乐。

Adapting to change is part of our industry's history and will be key to our future success.

"To be yourself in a world that is constantly trying to make you something else is the greatest accomplishment."

数学不是一项观赏性运动。你必须亲自去做才能理解它。