单项选择题 The Tang Dynasty was an era of extensive cultural exchange betweenChina and the world. The products and artifacts of the ancientcivilizations in the world gathered in ( ).

问答题 羊毛和蚕丝主要组成成分是[填空(1)] 。

单项选择题 “似至晦实至明；似至繁实至简；似至难实至易”是徐光启对（ ）的评价。 A、九章算术 B、几何学 C、几何原本 D、算术学