请仔细阅读下面含动词不定式的句子,在横线上写出括号部分在句中分别作什么成分?
1、We have got lots of things (to do).
2、They tride (to help)the poor children in the countryside.
3、The boy arrived at the railway station early (to catch)the train.
4、It’s nice (to see)you here.
5、My dream is (to travel)around the world.