the problem is that we are late.中that为什么不能换成what,可以讲一些基本的句子成分吗?比如定语从句中where which of which 等的区别,我觉得对基本句型掌握的不太好,还有对一些with 复合结构不明白,比如：with his interest in studes almost _是用lost还是being lost?对及物不及物动词怎么看呢?能不能讲一下aim的用法，the boy,aiming at winning champion,这儿用ing形式，为什么在the project,aimed at,,,中就使用ed了呢

the problem is that we are late.中that为什么不能换成what,可以讲一些基本的句子成分吗?
比如定语从句中where which of which 等的区别,我觉得对基本句型掌握的不太好,还有对一些with 复合结构不明白,比如：with his interest in studes almost _是用lost还是being lost?对及物不及物动词怎么看呢?
能不能讲一下aim的用法，the boy,aiming at winning champion,这儿用ing形式，为什么在the project,aimed at,,,中就使用ed了呢