front line

• 指冲突、斗争或某一领域中最前沿、最开放的位置，如军事行动、疫情期间的医疗工作或社会活动。也指最前线、最前沿的岗位或阵地。

Refers to the most advanced or exposed position in a conflict, struggle, or area of activity, such as military combat, healthcare during a pandemic, or social activism.

1. Military combat zoneB2formal

   The area where opposing military forces engage in combat, closest to the enemy.

   前线

   • The soldiers were sent to the front line to defend the city.
   • Conditions on the front line were harsh and dangerous.
   • He served on the front line for over a year.

2. Direct contact with customersB2formal

   The part of an organization that deals directly with customers or the public.

   一线

   • Customer service representatives are on the front line of the company.
   • Front-line workers often face the most challenging situations.
   • The front line staff need excellent communication skills.

3. Leading position in a fieldC1formal

   The most advanced or active position in a particular area of activity or development.

   前沿

   • This research is on the front line of cancer treatment.
   • The company is on the front line of technological innovation.
   • Activists are on the front line of the fight for social justice.