The man ---- (visit) your school is our headmaster.

The man visting (visit) your school is our headmaster.
动名词做定语,表示正在参观的…………
那个正在参观你们学校的人是我们的校长
The ground is covered with fallen(fall) leaves
The ground is covered with fallen leaves.(满地落叶).fallen 过去分词在这有形容词作用,所以 fallen leaves 是一个名词短语,表落叶.前句中,...is covered with 其后要加名词.