a quick question: how to add comments for several lines at the same time

[lina]

Hi,

When I use vim (how can I add comments for several lines at the same time,
not one by one)
add #

are there some trick? (without using some package:
http://www.vim.org/scripts/script.php?script_id=1528  )

Thanks ahead,

-- 
Best Regards,

lina