英文an obligation同埋可數問題

We were under obligation to finish the work in a satisfactory way.

2011-04-07 15:34:43 補充：
第1:我想問I have no friends 明明冇但係就要+s呢? No:作數形容詞 例如： He has no books. * "He has no book."亦可，"no"後可用單數。 He has no brothers/brother.http://www.npc.edu.hk/staff/~ngtungying/english_grammar/lessons/lesson18.htm
第2:obligation係 uncountable 同countable咁佢點數呢? 同埋 點解成日都加an呢?可用係 uncountableWe were under obligation to finish the work in a satisfactory way. 我們有義務圓滿地完成工作。亦可countableWe were under (an) obligation to finish the work in a satisfactory way. 我們有(一份)義務圓滿地完成工作。

例句一：
用friends是正正是一個寫法把一樣實在的東西(有一個朋友, 兩個朋友，幾個朋友，甚至是一班朋友)的countable詞generalize成為非量化詞，所以雖然數量上是零，規則上應該是「單數」，但由於意義上是汎指所有稱為「朋友」這東西，或如果你要用量化的想法是「所有朋友」這意識，所以才會加s，以包含這意思。

例句二：
nobody has an obligation to do anything
這句是錯的寫法，說negative(非/負面)的用詞事，nobody所要做的便不會用有量的數值詞an ...，而要用any ...
全句應該寫為：
nobody has any obligations to do anything.
這裏的obligation也會用上+s，理由跟上句一相同。

第 1

I have no friends. ( 如果 friends in general 要 +s )

Another example: Do you have any friends? No, I don't have any friends. ( friends in general 要 +s )


但係 friend 不 要+s , 如果 friend 係 specific (特定) friend

Example:
Do you have any friend who would be interested in working on Sunday?
No, I don't have any friend who would be interested.


第 2

She has an obligation to do something

obligation 係抽象名詞 abstract noun, 同 countable 或 uncountable 沒有相關

countable 同 uncountable 係 關於 concrete nouns 具體名詞 ( air or water is uncountable, trees and chairs are countable etc.)

Example:
He has an obligation to respect the law.
There are several obligations attached to the job.