INFINITIVES
	after certain verbs 
		(He tried to fly with his hands, but he failed to get off the ground.)
	after verbs plus objects
		(I caused him to laugh.)
	before or after actions to express purpose
		(We went home to get some rest.  To get some rest, we went home.)
	after adjectives of emotion
		(pleased to meet you)
	after nouns that they describe
		(a test to take)
	after "it" plus certain adjectives
		(It is hard to learn English.)


EXCEPTIONS
	make him pay
	*make him to pay
	let him pay
	*let him to pay


GERUNDS
	as subjects (Doing exercise is healthy.)
	as objects of certain verbs (We encourage doing exercise on a regular basis.)
	as objects of prepositions (They talked about doing regular exercise.)


REDUCED ADJECTIVE CLAUSES
Certain adjective clauses can be reduced--when the subjects are the same in both the dependent and independent clauses--by dropping the subject and changing the verb to a gerund.

	Before he came, he called.  -->	Before coming, he called.

While, before, and after are not deletable.  When is usually when the clause is in the past, and because always is.

	Before arriving, he called.
	After arriving, he started drinking.
	While drinking, he dreamed about living in a beachside mansion in Hawaii.
	Not paying attention, he dropped the glass on the floor.
	Seeing the liquid on the floor, he sighed and thought about Hawaii again. (WHEN)
	Knowing he would have to clean it up, he left early. (BECAUSE)
	When dreaming, you should not hold a drink in your hand.

    Source: geocities.com/markalvesesl