The modern atmosphere supports many forms of complex life that would not have been able to exist in Earth's first atmosphere because the oxygen level was too low.

现代大气层支持着许多复杂的生命形式，而这些生命在地球最初的大气层中是不可能存在的，因为当时的氧气含量太低。

youdao

In these days the pre-industrial city in America functioned as a complex and varied organizing element in American life, not as a simple, homogeneous, and static unit.

在这些日子里，美国未工业化的城市在美国人的生活中是一个复杂而多样的组织元素，而不是一个简单的、同质的、静态的单位。

youdao

Complex life evolved on the Earth's surface, but not on Mars or other planets in the solar system because on those planets, early surface life was killed by UV radiation.

复杂的生命在地球表面进化，而不是在火星或太阳系的其他行星上，因为在那些行星上，早期的地表生命被紫外线杀死了。

youdao

The puppeteers train for many years to move as one in bringing the puppet to life to act in complex theater productions.

VOA: special.2009.09.23

Located in the Main Street Life complex, a renovated textile factory, The Bioscope shows a programme of African-interest features as well as international films and documentaries.

BBC: Johannesburg��s hip transformation

Whether filming hippos in the clear water of Mzima Spring, flamingo chicks in a dried-out soda lake or the complex layers of life within a massive baobab tree, the Roots always let their subjects tell their own stories making astonishing discoveries along the way.

ECONOMIST: Animals in Africa

The scholars found a complex but clear series of connections between maternal health and the offspring's fatness in later life.

NPR: Rabid Reader: 'Fat Land' and U.S. Supersizing