Allergic reactions can occur when the immune system over reacts to innocuous substances.
Allergic reactions can occur when the immune system over reacts to innocuous substances.
过敏反应可能发生当免疫系统起反应对无害物质。
Allergic reactions can occur when the immune system over reacts to innocuous substances.
过敏反应可能发生当免疫系统起反应对无害物质。