How can I indicate that a certain action is either already done or waiting to be done?

1. How do you use past simple and past perfect?
2. What is perfect continuous tense with example?

How do you use past simple and past perfect?

These two tenses are both used to talk about things that happened in the past. However we use past perfect to talk about something that happened before another action in the past, which is usually expressed by the past simple. For example: "I had already eaten my dinner when he called."

What is perfect continuous tense with example?

Examples of the Present Perfect Continuous Tense

We have been working as doctors for two years. He has been working as a doctor for two years. She has been working as a doctor for two years. They have been working as doctors for two years.