for unfinihed actions that started in the past and continue to this date. We often use for or since with it. I have been waiting for a pcr test for about 3 hour

we use since with a fixed time, "I haven´t seen snow in Vitoria since I was a child". For is used with a period of time, " I havent seen snow in Vitoria for 5

no we cannot.

When something is always true, for permanent or fixed situations, habbits or things we do regularly, we also use it for short or temporary actions...

Sts own answer

Most do not and change if a gerund is added.

Unfinished actions, finished actions in the past that have a connection to the present.

yes, time tabled events .....

sts answer

...have+past participle

Present continous. We use it for differrent types of temporary situations.

sts own answer..