I'm troubled by his lack of seriousness.

Père David's deer, also known as the 'four unlike', is a species of deer native to China and is listed as an endangered species.

In genetics, linkage disequilibrium is a very important concept.

He always shows a frustrated attitude.

He always feels frustrated.

The success of this project is influenced by a lot of uncertainty.

Sometimes, irrational things happen in this world.

I'm just amazed at the absurdity of this world.

Happiness is a mass noun, you can't count it.

Learning irregular verbs is difficult.