The past progressive tense is used to talk about a past action that took place over a period of time. This tense uses the following formula:
Future perfect is used to talk about things we will have completed at some point in the future. This is how it is formed:
Conditional sentences are used to express real and unreal events. The real events are usually true or at least possible. The unreal events are usually hypothetical and can describe what could have happened or what we wish could have happened.