Question

1) "I am filled with sadness."
Can you explain the grammar rules for using "filled" instead of fill?

2)"We visited the Detainees (sic) camps and we saw the jails." What does '(sic)' mean?

3) Sometimes we see 'p.s.' at the end of a letter. What does it mean?

Answer 1

1. The verb "am filled" is the passive form of "fill" in this sentence.
http://grammar.ccc.commnet.edu/grammar/passive.htm
Scroll down to the chart called Passive Verb Formation, and you'll see that all tenses in passive are formed by using the past participle form of a verb plus an auxiliary verb (form of the verb "to be").

2. To indicate an error in quoted material:
http://www.protrainco.com/essays/usage.htm
Scroll down to Sic? Sic! Sic!

3. The abbreviation PS or P.S. (note that the letters should be capitalized) stands for the Latin <i>post script</i>:
http://en.wikipedia.org/wiki/P.s