单选题
I am writing to______ you most sincerely on your appointment as Headmaster of the Grammar School.
【正确答案】
D
【答案解析】解析：congratulate(sb．on sth．)vt．祝贺，向……道喜。salute v.(向……)敬礼；向……表示敬意。applaud v.(向……)鼓掌，(向……)喝彩；称赞，赞许。hail vt．欢迎，向……欢呼。(注：salute，applaud和hail三个动词的宾语后而都不跟介词on短语)