How to add extra details to card?

There are two ways to add extra details to card:

(a) Extra Property

Example 1

extra:: Tokyo, Japan’s busy capital, mixes the ultramodern as well as the traditional, from neon-lit skyscrapers to historic temples.
The capital of Japan is {{cloze Tokyo}}.

(b) Extra Org Blocks

Example 1

The capital of Japan is {{cloze Tokyo}}.
#+BEGIN_EXTRA
Tokyo, Japan’s busy capital, mixes the ultramodern as well as the traditional, from neon-lit skyscrapers to historic temples.
#+END_EXTRA