usually will in a sentence represent future?
and would represent past or present?
will can express willingness, intention, and prediction.
would can express willingness, insistence, customary, hypothetical, and probability
Originally Posted by ccc.commnet
Uses of Will and Would
In certain contexts, will and would are virtually interchangeable, but there are differences. Notice that the contracted form 'll is very frequently used for will.
Will can be used to express willingness:
I'll wash the dishes if you dry.
We're going to the movies. Will you join us?
It can also express intention (especially in the first person):
I'll do my exercises later on.
specific: The meeting will be over soon.
timeless: Humidity will ruin my hairdo.
habitual: The river will overflow its banks every spring.
Would can also be used to express willingness:
Would you please take off your hat?
It can also express insistence (rather rare, and with a strong stress on the word "would"):
Now you've ruined everything. You would act that way.
and characteristic activity:
customary: After work, he would walk to his home in West Hartford.
typical (casual): She would cause the whole family to be late, every time.
In a main clause, would can express a hypothetical meaning:
My cocker spaniel would weigh a ton if I let her eat what she wants.
Finally, would can express a sense of probability:
I hear a whistle. That would be the five o'clock train.