Question

16．你应该准时到．让人家久等是不礼貌的．
You have to go there on time．It's not polite to keep others waiting for you so long．

Answer 1

分析 It's not polite to keep others waiting for you so long．

解答 答案：It's not polite to keep others waiting for you so long．表达的是客观事实用一般现在时，表示做某事是怎样的用it's+adj+to do sth，礼貌的polite，故It's not polite to，让某人一直做某事keep sb doing sth，他人others，等某人wait for sb，时间久so long，故答案是It's not polite to keep others waiting for you so long．

点评 It is adj+of sb to do sth 
答：1）for sb．常用于表示事物的特征特点，表示客观形式的形容词，如easy，hard，difficult，interesting，impossible等：
　　 It's very hard for him to study two languages．对他来说学两门外语是很难的．
2）of sb的句型一般用表示人物的性格，品德，表示主观感情或态度的形容词，如good，kind，nice，clever，foolish，right．
　　 It's very nice of you to help me．你来帮助我，你真是太好了．