preposition的問題

* My sister is often crying for nothing. =
=沒爲某件事(=無端端)而哭起來. " as " 不宜用在此句.

* My sister is often crying as raining. = 喊到像淚如雨下.

*用不同的preposition帶領是各有其意思的.

*be=is動詞之後是補語=complement.
often crying for nothing. 是副詞片語.
(因crying是一行為去描述My sister.)

*例: My sister is a good girl.名詞片語.去形容My sister.

thanks for......=為了....而多謝.

thanks of......=of有關...你的...thanks幫忙, (我是非常感激的)

各有不同的表達.

2012-03-10 17:50:00 補充：
thanks to.....=to向....某某....道謝.

用cry for. 原因 cry for 是verbal phrase (cry to, cry out, cry over)
for nothing 也是 phrase, work for nothing,從什麼角度看

[often crying _ nothing ] 不是名詞片語. is crying 是 main verb,
part of main verb不可能 include在 noun phrase中, noun phrase是作subject, object or complement.

2012-03-10 01:24:56 補充：
thanks for 和 thanks of 不是一樣
He thanks her. (thanks - verb)
He left without a word of thanks. (thanks - noun)
“No, thanks.” (thanks - interjection)
Preposition after thanks:~ for, to
少用thanks of , Thanks of Congress, greatest thanks of all
of thanks 比較 common, a letter of thanks, a vote of thanks