The equilibrium length of this spring is 5 centimeters.

He prefers natural foods.

Calculating the natural logarithm is an important part of mathematics.

His car spontaneously combusted all of a sudden.

This wood may spontaneously combust if the humidity is high.

Natural rights are rights that humans have from birth.

We must strive to protect the natural environment.

He claims to be a warrior for freedom of expression, but in reality, he's just someone who uses derogatory words.

Natural language understanding is an important field of artificial intelligence.

We are planning to visit the nature reserve this weekend.