My grandfather is already eighty years old.

Soohachi is my best friend.

He is learning about the history of Yagyū.

There are eight students in our class.

There are eight students in our class.

The Great Vowel Shift played a significant role in the history of English.

A diphthong refers to the phenomenon where two vowels are pronounced consecutively within a single syllable.

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 front vowel is a vowel that is articulated with the front part of the tongue.