He is a regular customer of this restaurant.

His opinion is always objective.

He is of Hakka ethnicity.

Ebola virus disease is highly infectious and can cause severe symptoms.

He used his alphanumeric skills to create a computer program.

Suro is my best friend.

Saburo is my best friend.

Kazumasa is my best friend.

A composite number, unlike a prime number, is represented by the product of two or more natural numbers.

Amicable numbers refer to a pair of natural numbers that have a special relationship in number theory, a branch of mathematics.