重任 (zhòng rèn): heavy responsibility

My boss handed the entire project to me; this is a heavy responsibility, and I must go all out.

As doctors, saving lives is our heavy responsibility; we cannot be the least bit careless.

He took on the heavy responsibility of supporting the family at a young age, which made his parents very gratified.

Protecting the environment is a heavy responsibility for every citizen; we should start with small things around us.