一旦

Once an opportunity slips away, it is gone for good.

If you want to do well, you can't give up once you choose.

They spent four years together in college, and once they were apart, everyone felt bad.

Once the place collapsed, the consequences were unimaginable.

Once we fail the exam, we will put off graduation.

Once the subway is completed, the traffic jam will be greatly alleviated.

Once Chinese learns, it can't be let go any longer.

Once the plan is all set, you should keep to it.