I have often been asked how my plays come about. I cannot say. Nor can I ever sum up my plays, except to say that this is what happened. That is what they said. That is what they did.

人类活动已成为塑造地球气候的重要力量。

The improvement of the productive powers of labor, and the greater part of the skill, dexterity, and judgement with which it is anywhere directed or applied, seem to have been the effects of division of labor.

数学不是一项观赏性运动。

教学不是传递知识，而是为知识的产生或构建创造可能性。