(...) 是我加的,或者是更改过的词句
[...] 是适合的用法,包括语法,标点符号的修正等
-------------
When my eighteenth birthday [arrived],I [was away from] home.
In order to celebrate such (an) important day with my dear parents,I wrote a long letter[.] In which I thanked [them] for having raised me for (the past)18 years,and expressed my love for them.
Later,(my) mother [told] me (that) when she read the letter,[her eyes were filled with tears].(My) father (on the other hand,) appeared very cool.
(However),he [later read] it carefully (by himself).He (then) [placed] it up into a desk drawer.I can imagine the scene [clearly] because I know [him well].Being a man with few word,he prefers to show his love for me in a silent way.