This animal is a protected species, so you must never touch it.

Using abbreviations makes the sentence shorter.

I'm thinking about what to do on the weekend, but I want to find some new entertainment.

The traffic light turned red, so I stopped.

His opinion is always rational.

Please check before you throw away the eggshell.

He is serving as the president's guard.

He drew a pentagon on the blackboard.

What is this mixture made of?

Metalinguistics is an important concept in linguistics.