That man-child is still living in his parents' house.

He is called a 'kid's room uncle', and is alienated from society.

I reserved a single room.

We booked a double room.

He learned the movements of the solar system using an orrery.

The heliocentric theory is the idea that the sun, not the earth, is the center of the universe.

We installed solar batteries on the roof of our house.

I have been communicating with him for a long time.

He hiked the mountain alone.

He is trying to cut back on sweets because of his hyperglycemia.