He is suffering from the symptoms of black hairy tongue.

He is conducting research on the radula of mollusks.

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

Early detection of cervical cancer is important through regular health check-ups.

In Sanskrit phonology, retroflex sounds play an important role.

A back vowel is a sound where the back of the tongue approaches the palate.

Back vowels are vowels that are pronounced using the back of the tongue.

A coronal is a sound that is pronounced using the tip or the upper part of the tongue.

Retroflex sounds are difficult to pronounce.

Retroflex is a phonetic feature that does not exist in Japanese.