1 How crowded the street is when people went to watch football match last Sunday
表语 主语 系词 时间状语
2 When it rains ,I go to school by bus
时间状语 主语 谓语 方式状语
3 Since you are free today,you had better help me with my Chinese
原因状语 (既然你今天有空) 主语 谓语部分
4Whether he will leave today or tomorrow makes no difference to me
主语从句 作主语 主句的谓语