双引号内是公交车司机说的话，单引号内是男孩死前说的话。I'm sorry 前漏掉了单引号的前半部分。原句应为：

 " No use. I tell you he's dead. " The driver looked down at the boy's still body. " He never even said he felt bad, " he muttered, " just tapped me on the shoulder and said, quietly, 'I'm sorry. I have to get off at the hotel. ' That's all. Polite and apologizing. "   

如果我们忽略双引号，只注意男孩说的话，就可以看出polite和apologizing的语法作用：

He （the boy) never even said he felt bad,  just tapped me on the shoulder and said, quietly, I'm sorry. I have to get off at the hotel. ' That's all. Polite and apologizing. "   

Polite and apologizing 前省略了 He was.

译文：

“没用的。我告诉过你他死了。” 司机低头看着男孩一动不动的尸体。“他一直没说他感觉不好，” 司机低声说道，“只是拍了拍我的肩膀，轻声地说 ’对不起，我得在旅馆下车。‘ 他只说了这些。很有礼貌，带有歉意。”