英语语法分析

Since I have been at this school we have three headmasters.

自从我到这所学校以来已有过三位校长了。

Since I was at this school, they have had three headmasters.

自从我离开这所学校，他们已换了三个校长了。

Vice headmasters Zhang Xiaochun and Che li 'an visited Australia for research.

张晓春、车立安副校长赴澳大利亚考察。