請問 can,could,may,could,would...呢d點用架??

can-----多用於肯定句或問句.
e.t.c.------You can do it.
Can you do it?
He can do this different sum.
Can he do this different sum?
could------同上,但用於過去式(past tense)
He could do the sum.
Could he do the sum?
may------can 的禮貌形
He may help us.
May he help us?
should---shall 的 past tense
I should tell him the truth.
Should I tell him the truth?
would----will 的 past tense
I would help her to do the housework.
Would I help her to do the housework?