请和你的同学一起认真分析下列句子，并补全所缺内容。这种学习方式能逐步提高你理解长难句的能力。
1. But it was evident that ideas were changing in the 13th century when painters like Giotto di Bondone began to paint religious scenes in a more realistic way. (P2)
【分析】① 本句是一个复合句，句子的主干结构为：形式主语（it） + 系动词（was） +表语（evident） +主语从句（that ideas were changing in the 13th century）；
② when painters like Giotto di Bondone began to paint religious scenes in a more realistic way是定语从句，修饰________。
