Selecting a dynamic checkbox in selenium using regex

I am trying to select a checkbox whose ids are generated dynamically but couldn't solve it.

Tried following

Selenium.check("id=regexp:ctl00_cphMa开发者_Python百科in_cbx_[a-zA-Z0-9_,]*")
Selenium.check("xpath=(//input[@type='checkbox'])[position()=1]")

Also this check box has only dynamic id, no name etc. any idea what I am doing wrong.

Regards

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have you tried selenium.check('xpath=//input[@type='checkbox' and starts-with(@id,'ctl00_cphMain_cbx_')])

That should get what you are after