grammar問題... is/am/are

當兩樣野經常一齊提到，被當作同一樣野時，singular noun 都係可以用o既。Heat and humidity（熱力同濕度）如果你心裏面係分開o既兩樣野，請用 are；但如果你諗緊o既（例）人對氣溫o既感覺／水o既沸點，呢ｄ情況有可能係二而為一o既。另一例子係 bread and butter ，兩樣合埋係外國人早餐不可少o既部份。
不過講到人，除非係集合名詞如 team, family, government 可以 is/are 都得，否則多過一個都係用 are 架啦。我地只會數人頭，唔分先後。
講到咁，你「最後」o個個問題係咪都已經答左呢？
圖片參考：http://hk.yimg.com/i/icon/16/3.gif



2007-07-24 00:28:53 補充：
漏左一個「例外」：計加數時，老外會話 One and one is two. 一加一等於二。樓上講o既 the sum of... 其實就隱藏左o係呢種 X and Y is Z o既出口計數句子中。但老外真係計數計出聲時，係唔會出整地講 The sum of X and Y is Z 架嘛。同理 three times three is nine，但佢唔用 and，似乎已唔係你問o既範圍啦。

wrong explanation:
you explained: 當兩樣野經常一齊提到，被當作同一樣野時...
If so, what will you say if you are talking about your shoes?
Will you say: Both of my right shoe and left shoe IS dirty.
I dont think so.

Heat and humidity 可能係一樣野, 呂係兩樣野所以用is掛
Mary and I 用are, 因為Mary and I 係用We, 而We 係用are

I am
He/She is
You are
We are
They are
It is

e.g.1) X and Y 係 They, 用are
e.g.2) The sum of two numbers x and y is 26.
The sum of two numbers 即係 it , 所以用is