13．---How is it going now？ ---Terrible．The warmer the weather is，the faster the fluwill spread （天氣越暖和，流感就會傳播得越快）．（spread） ---Something must be done to stop it．
12．---Mr．Black，could I hang out with my friends this afternoon？ ---No，you can't，David．You may be kicked off unless you work hard． （如果你不努力工作，可能被開除）．（unless）
