It’s ten years since the scientist ___on his life’s work of discovering the valuable chemical.[ ]

I will compete ______ Mary ______ the first prize in the competition[ ]

Healthy eating along with regular exercise _______ important for your health．

The rescuing soldiers in the helicopters ______ to land on that area, but failed again.

ou enjoy meeting your old schoolmates at the party last week—Yes, I did. We ________ each other since we graduated from college.