What is the verbless clause?

I want to give some examples of a special type of clause.

1) Too tall to enter the room, he remained standing at the door.

2) Whether successful or unsuccessful, he always puts his best efforts in his work.

3) To nervous to move, she stood on the floor, trembling.

4) Laughed at, they lose heart.

5) He declares the meeting open.

This are the some examples of verbless clause. I want to know more about verbless clause. I searched in net a lot, but unfortunately what I found were not sufficient. Those were not enriched with proper description. I want to know the ways used to express verbless clauses into other way. I want to learn how these clauses are being formed. Please mention some useful links/PDF files that are related to this topic and able to fulfill my demand.