global warming

Algae are simple plants that grow in or near water and do not have ordinary leaves or roots. They can be very small like green spots or very large like seaweed found in the ocean.

An amphibian is a type of animal that can live both on land and in water. Most amphibians, like frogs and salamanders, start their lives in the water and move to land as they grow older.

An asteroid is a large rock that travels through space and orbits the sun. It is much smaller than a planet and is mostly made of rock and metal.

Astronomy is the scientific study of stars, planets, and everything else in space. It is the branch of science that looks at how the universe works outside of Earth's atmosphere.

Atmospheric pressure is the weight of the air in the sky pressing down on the Earth. It changes depending on the weather and how high you are above the sea.

一种毛皮厚实、体型大、力量强的哺乳动物。

骆驼是一种背上有 一个或两个驼峰的大型动物。

伪装就是通过模仿周围的环境来隐藏自己。这能让动物或人与背景融为一体，从而保护自己不被发现。

指森林的顶层，由树冠组成。

峡谷是一种两侧陡峭的深谷，通常有河流穿过。它是水流经过多年侵蚀而形成的自然景观。