Para pedir desculpas, I'm terribly sorry e I'm really sorry são fortes e calorosas. I apologize é um pouco mais formal.
Pedindo desculpas
I'm terribly sorry — I'm terribly sorry for the wait.
I apologize — I apologize for the trouble.
I'm really sorry — I'm really sorry about this.
Experimente: Amina: There is a problem with my room. Hiroshi: ___ What is wrong? Hiroshi works at the hotel and wants to apologize. Which fits? (I'm terribly sorry. / Excuse me, but / I'm not happy with) Resposta: I'm terribly sorry. — I'm terribly sorry é um pedido de desculpas, o que combina com a resposta de Hiroshi. Excuse me, but e I'm not happy with servem para reclamar, então nenhuma das duas pede desculpas.
Reclamando com educação
Para reclamar de um jeito educado, comece com Excuse me, but, depois diga There's a problem with ou I'm not happy with antes da coisa que está errada.
Excuse me, but — Excuse me, but this is cold.
There's a problem with — There's a problem with my room.
I'm not happy with — I'm not happy with the noise.
Experimente: Sofia: How is everything in your room? Diego: ___ the noise. I can't sleep. Diego wants to complain politely about the noise. Which fits? (I'm not happy with / I apologize / I'm really sorry) Resposta: I'm not happy with — I'm not happy with introduz uma reclamação educada, o que combina. I apologize e I'm really sorry são pedidos de desculpas, então nenhum dos dois é uma reclamação.