All of the following are mentioned in Paragraph 1 as characteristics of Caulerpa taxifolia
A. the world's largest algae.
B. the ability to make food on its own.
C. a slender, green appearance.
D. an invader of foreign ecosystems.
A．privilegedB．embarrassedC．energeticD．attractive
A. privileged
B. embarrassed
C. energetic
D. attractive
What reason is given for the stability of the arch？
A concrete foundation supports the arch.
B. The arch is built with wedge-shaped blocks.
C. The Romans made a strong type of concrete.
D. The pressure flows up to the keystone.
梵蒂冈宫的三幅壁画：《雅典学院》、《巴尔纳斯山》和《圣典辩论》是意大利文艺复兴时期艺术大师()的作品。
A. 拉斐尔
B. 米开朗基罗
C. 达·芬奇
D. 提香
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