[新知导引]
诵读下列例句并感知画线部分的共性
1．There are many reasons why this has been possible, but one of the main factors has been the Chinese writing system.
2．Emperor Qinshihuang united the seven major states into one unified country where Chinese writing system began to develop in one direction.
3．I told my mum that I wanted to give up, and that I would never live in a country where German was spoken.
4．I finally understood the reason why my mum had encouraged me not to give up.
5．Then I saw an advertisement that offered a wonderful summer course, and that was the day when I decided to take on a new language.
6．The time when I first met Nelson Mandela was a very difficult period of my life.
