我觉得是atAt the boy’s last remark the bookseller looked at him.听到那男孩最后的那句话，卖书的人就看着他。句中第一个介词at表示动作、感情的原因，意思是“因……而；见（听）……而；一……就”。又如：I was frightened at the news.我听到那个消息吓了一跳。She was very pleased at her son’s achievements.她因儿子取得的成绩而非常高兴。The baby stopped crying at the sight of his mother.这婴儿一看到母亲就不哭了。...
