31.請(qǐng)根據(jù)下面的這封信寫一封回信,80詞左右. Dear Alice, I like your programs very much.I'm writing to ask you something about American social customs.My American friends want me to join them in their dinner party.I'm very happy and have decided to go,but I'm a bit worried about it.The social customs in my country are different,so I'm afraid of making some mistakes. Should I bring a present,such as sweets or flowers?Should I arrive on time or late?At the dinner table,how can I know which fork or knife to use?How can I let the family know that I'm thankful for their kindness? Yours, Xiao Qiang