下列图形中∠1与∠2互为对顶角的是（　　）

选择合适的选项。

（____）1.He is talking at the cinema.

（____）2.We are playing with dog.

（____）3.She is coloring at her desk.

（____）4.They are working in the library.

（____）5.They are walking on a bridge.

A. Keep to the right.

B. Talk quietly.

C. Take turns.

D. Keep your desk clean.

E. Work quietly

阅读下列材料：

子曰：知之为知之，不知为不知，是知也。  

——《论语•为政》

请回答：

谈谈你对孔子这句话的理解，从中你受到什么启示?