His double personality confuses me.

He bears a double responsibility.

She has single eyelids.

A new polymer was produced by this chemical reaction.

He likes to take a walk in the park at dusk.

He understands the meaning of the proverb 'Teaching is half learning', which means that teaching leads to one's own learning.

He repelled the enemy using the heavy rattan bow.

Tritium is one of the radioactive isotopes.

Haplology is a part of linguistics, referring to the phenomenon where a part is omitted when the same syllable repeats.

His actions always have a duality.