Would or Will; Could or Can?

Question

What's the difference of Would and Will, and Could and Can, and when do you use them?

for example:
i (will/would) go to the party tomorrow night.
she (can/could) dance all night long without feeling tired.

Answer 1

You use will to indicate that you hope,think,or have evidence that something is gong to happen or be the case in future.
You use the word would , when you are saying that you believed, hoped or expected to happen or be the case.You expect certain thing to happen but are not sure of it.
You use can to indicate that someone has the ability or opportunity to do something.eg. Don't worry yourself about me.I can take care of myself.
You use 'can' to indicate that something is true sometimes or in some circumstances.
You use 'could' to indicate that someone had the ability to do something.It also indicates that something sometimes happened.

Answer 2

Among some of the differences are levels of politeness and the context of the conditional.

Answer 3

It has to do with past participle and present participle. It depends on the construction of the sentence and the paragraph.
Ex. She wanted to say no but couldn't. (the first verb 'want' is in the past tense, therefore the next verb 'can' must be past participle)
She wants to say no but can't. ('want' here is in present tense, so 'can' should be present participle)

Answer 4

This site may be useful: http://www.wsu.edu:8080/~brians/errors/errors.html#errors

:)