Life is a series of vicissitudes.

I am studying Modern English.

The history of the British Empire occupies a particularly important part in world history.

The artificial satellite is orbiting around the earth.

The study of nekton is an important part of marine biology.

According to the Imperial Headquarters announcement, the war situation is progressing favorably.

In organic chemistry, we use the Newman projection to represent the three-dimensional structure of molecules.

The Fischer projection is a commonly used representation method in organic chemistry.

In organic chemistry, we use the Haworth projection to represent the three-dimensional structure of sugars.

In the organic chemistry class, there was an explanation of the Natta projection.