El infinitivo de perfecto continuo

[A] Forma

     to have been + participio de presente: 

• He seems to have been spying for both sides.

[B] Uso

     Se emplea principalmente después de verbos auxiliares y después de appear y seem, pero también puede usarse después de happen, pretend y la pasiva de believe, know, report, say, understand:

• He says he was talking to Tom. – He couldn’t have been talking to Tom. Tom wasn’t there.
• I was following Peter closely. – You shouldn’t have been following him closely; you should have left a good space between the two cars.
• He appears to have been waiting a long time =

= It appears that he has been waiting a long time.

• He pretended to have been studying =

= He pretended that he had been studying.