Analyse the following statements, according to the grammatical structures and their meanings in the text:

I. The clause “have made it more feasible” (l. 27-28) expresses an action that began in the past and continues to have effects in the present.
II. In the sentence “It would require enormous satellite structures” (l. 21), the verb form “would require” indicates a hypothetical situation rather than a real one.
III. In the sentence “making it work is no small task” (l. 21), the structure “making it work” functions as the subject of the sentence.
IV.The structure “it was dismissed as too costly” (l. 26) refers to a past passive construction in the simple past.

Which ones are correct?