He learned the old character form of 學 to study ancient documents.

He is dedicated to the study of immunochemistry.

Because her immune system is weak, she catches a cold easily.

Because he has immunodeficiency, he always pays attention to his health management.

Mucosal immunity plays a crucial role in protecting our bodies from pathogens.

People with strong general immunity are less likely to catch a cold.

He is an expert in immunology.

A healthy diet and moderate exercise help boost immunity.

He was born as an illegitimate child and experienced many difficulties.

My grandfather used to till his privately-owned rice field.