Look at this. What's this in English, do you know? Ah, it's a photo. Who's that in the photo? It's Li Yan. Li Yan is my good friend. She is a beautiful girl. Who's that? The boy in black? It's Jim. He is an English boy. He is very cool. He is my friend, too. We are all in Class 3,Grade 7. I like Jim and Li Yan.

台湾学者许倬云在描述中国古代政治制度时说：“帝国时代延续两千年的奥秘即在于，君主专制的刚性与官僚制度流动的柔性相结合。”这一论断说明了中国帝国时代政治制度的特点是

下列关于光合作用和细胞呼吸的叙述，正确的是（　　）

①发现杠杆定律和浮力定律的科学家是：____。

②他把古代希腊悲剧艺术推向成熟____。

③____是巴黎最古老、最高大的天主教堂。