The verbs in blue and green are modal verbs:
They don't actually have their own meaning, but rather change the meaning of a whole sentence (it's possible that..., it's certain that... etc.).
The simple form can refer to the present or the future:
The progressive form can also refer to the present or the future:
The perfect form can refer to a moment before now, before a moment in the future or before a moment in the past:
The same is true for the perfect progressive form:
Notice that the same form of a modal verb can refer to different times, so modal verbs can't be used to say when something happens. Other words and the context can tell us what time these verbs refer to.
The perfect form is the only way to refer to something before now, so we can't express the difference between the present perfect and past simple with modal verbs: