He was waiting in front of the house.

I ate half of the pizza.

I have been to Japan three times before.

He is an expert in entomology, especially knowledgeable about butterflies.

Insects are an important part of the natural world.

He is world-famous as an entomologist.

This is part of my collection, especially the Arabian cowry is rare.

I contacted him beforehand.

The depressed cowry lives quietly at the bottom of the sea.

Prepositions are an important part of grammar.