The ecosystem of this lake is very fragile.

In physics, the inertial frame of reference is a very important concept.

This system is very complex.

The house sold for a good price.

There is a state-of-the-art incubator in my laboratory.

This old battery is no longer usable.

I mixed the pancake batter with my new whisk.

He is well-versed in the use of hidden weapons.

He analyzed the light of the stars using a new spectroscope.

He spoke to the people at the assembly using a loudspeaker.