(1) これはあなたを幸せな気分)にする(であろう)物語です。
This is (that / make you happy / will /astory).
This is a story that will make you happy.
(2) 私は日本人によって親しまれている歌を歌うことが
できます。
I
can sing (is la song I loved by Japanese/
that),
I can sing
a song that is loved by
Japanese,
(3) 昨日来たはがきはコマからです。
( yesterday / the postcard / came (that)
is from Emma
The postcard that came yesterday
is from Emma