The Perfect Progressive tense in Czech grammar is used to describe an action that started in the past, continued over a period of time, and is still ongoing.

To form the Perfect Progressive tense, we use the auxiliary verb „být” (to be) in the present tense, followed by the verb „mít” (to have) conjugated in the past participle form, and the verb „být” in its past participle form.

For example, „Já jsem byl četl knihu” (I have been reading the book) or „Ona byla psala dopis” (She has been writing a letter).

The Perfect Progressive tense is commonly used when talking about actions that have recently been completed or are still in progress. It helps to emphasize the duration and continuity of the action.

It is important to note that the Perfect Progressive tense is not commonly used in everyday speech and is instead more commonly found in formal or written contexts.