3. be strict with sb. 对某人严格

　　Father is always strict with his sons. 父亲对子女经常要求严格。

　　比较：be strict in sth. 对某事物要求严格

　　Teachers are strict in students' homework. 老师对学生的作业要求严格。

　　4. lead to 导致，通向（to为介词）

　　Hard work leads to success. 努力通向成功。

　　All roads lead to Rome. 条条道路通罗马。

　　5．link...to... 将......和......连接起来

　　Can you link the clues to the criminals? 你能把线索和罪犯联系起来吗？

　　6. keep sb /sth +doing /done /adj. 让某人或事物做......

　　I'm sorry to have kept you waiting so long. 对不起，让你久等了。

　　You must keep your jewels locked up. 你得把珠宝饰物锁好。

　　Keep the classroom clean. 要保持教室清洁。(adj.作宾补)

　　注：用doing强调与sb/sth是主动关系且与谓语动词是同时或一直进行的；用done强调与sb/sth是被动关系且业已完成；用adj.强调sb/sth的状态。

　　三、课文长句难句剖析

　　1. In addition, he found two other deaths in another part of London that were linked to the Broad Street outbreak.

　　剖析：句中的that引导一个定语从句，修饰先行词two other deaths；先行词与定语从句之间被介词短语in another part of London所分隔。