保安的关键职责之一是确保大楼的安全。

One of the key ___duties of a security guard is to ensure the safety of the building.

教师的职责不仅限于授课，还包括引导学生的行为。

A teacher's ___duty extends beyond just delivering lessons to include guiding students' behaviour.

医生的首要职责是以病人的最大利益行事。

It is the doctor's primary ___duty to act in the best interest of the patient.