Can and should(20點)

Should 和 Can 是 auxiliary verb 一 種, (or helping verb), 後的main verb 是用base form of the verb.
Should + main verb [base form]

should do ~ right.
should did, should done, should does, should doing ~ all are wrong.

For passive voice,
Should + be + past participle
e.g. should be done.

你問題問, “can 和 should 後的(v.)是否100%不會轉tense?”
Be careful, there is another form for the main verb ~ perfect tense, continuous tense.

should + have + past participle
should have done

Should + be + present participle
should be doing

Example:
You should have done your homework by six o’clock yesterday.
Do 轉了done, 不過有一個”have” between “should” 和 “done”.

The homework should have been done by six o’clock yesterday. (passive voice)

Should 正常地是 for present and future 使用, 除非 should 是 past tense of “shall”.

還有Can 亦可以做 main verb.

2011-02-25 10:20:46 補充：
應該是說:
should + main verb [base form]
~ provided that there is no word between “should” and “main verb”.

can + main verb [base form]

我推薦您一個非常不錯的英語學習網站，里面有很多非常不錯的學習資源：

http://www.hkenglishstudy.info

希望可以幫到你!

Yes,after can should,we can not use any tenses.

no they won't change tense
To conclude:
Can (could), will (would), shall (should)
all acts like 'to'
the tense won't change after them.

would都唔洗的 100%唔會

係呀~除左could,can would.should,仲有must後面既(v.)都唔會轉架

You are absolutely right. Apart from can/could, will/would, shall/shoud, there
are more, like may/might, must/musn't, do/did, dare/dared or durst, etc.

係啊!can, should ,would,will,to都係唔洗+架

YES....

After verbs like Can, Can't, Should, Shouldn't... there tense wont change

2011-02-24 21:39:57 補充：
*their