O Present Perfect Continuous (have/has been + -ing) enfatiza a duração de uma ação que começou no passado e ainda está em progresso — ou acabou de terminar com efeito visível.
I have been studying for two hours. (e ainda estou a estudar)
She has been working on that project since Monday.
You look tired — have you been running?
Sujeito + have/has been + verbo-ing.
I/You/We/They have been waiting.
He/She/It has been raining.
Negativa: She hasn't been feeling well.
Pergunta: How long have you been studying?
PP Simples → resultado/quantidade. PPC → duração/processo em andamento.
I have written three emails. (resultado — quantos)
I have been writing emails all morning. (processo — duração)
She has eaten the cake. (resultado — acabou)
She has been eating all day. (hábito/duração)
Cuidado com estas confusões: