美国用英语怎么表达?

South America separated from Africa 200 million years ago.

2亿年前南美洲和非洲分离。

South America and Africa separated 200 million years ago.

南美洲和非洲于2亿年前分离。

The proportion of small cars on America's roads is increasing.

美国公路上小汽车的比例在逐渐增加。

America is the land of freedom and opportunity.

美国是一个拥有自由与机遇的国度。

I lived in America when I was little.

我小时候生活在美国。