I got kind of confused of these words ending with lise/lize like realize/legalize/recognize ... I wanna ask for British English the root form of these words end with se or ze ? How about when they are past tense form ? sed or zed ?
BrE generally uses the -s- in all forms and AmE generally uses the -z- in all forms.
The words you mention are all words that are spelled differently in British English and American English. There are quite a few of them (color/colour, theater/theatre, realize/realise etc.) If you are concerned with using a specific spelling standard, I would advise you to google "british american spelling" or something of the sort, to aquire some basic knowledge in the matter. Also, be sure to set your spell checker to the correct standard in your word processor.

To answer your specific question, British English uses the -ise forms in both present and past tense.
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So in British English there's no ze for words ? Everything ends in se ? ( Example : Randomise/Memorise/Pulverise ) ... Sometimes I find it confusing to see some words like prize and put them prise instead ..
For the first time in history, Google use 'se' instead of 'ze' in one of their global campaigns..
http://www.seospecialist.co.uk/google-recognise-british-spelling-in-legalise-love /

Will it continue?
JustForFun I get kind of confused of by these words ending with lise/lize like realize/legalize/recognize ... I wanna would like to ask for if British English the root form of these words end with se or ze. ? How about when they are past tense form? sed or zed?
Typically, the British form is ise; the American form is ize. Past tense forms and derived noun forms also differ this way.

Nevertheless, I've read that Oxford University (British) prefers ize. The Oxford Dictionary web sites sometimes state that both ize and ise are used in Britain.

Note also that the following words are spelled the same worldwide, in apparent contradiction to the "rule".

advertise, advise, arise, comprise, compromise, demise, despise, devise, disguise, excise, exercise, franchise, guise, incise, revise, rise, supervise, surmise, surprise, televise, and wise

capsize, seize, size, prize

See http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences#-ise.2C_-ize_.28-i...


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The spelling prise is often used when the word is used in its transitive verb form (which is very similar to the verb "pry").
I notice that AmE spellings have crept into BrE. Nowadays,BrE dictionaries give both -ize and -ise versions for such words..In fact, it seems to me that the -ize form is now preferred to the one with -ise.

PS Please ignore my earlier post. I could amend it.