# the sume of 跟the number of 單複數

1. In plane gemetry, the sum of the internal angles of any triangle

have always equal to 180 degrees.

2. Because of protective laws and captive breeding efforts in both the Unithed States and China, the number of cranes is slowly but steadily increasing.

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1. In plane geometry, the sum of the internal angles of any triangle

is always equal to 180 degrees. 在平面幾何中，任何三角形的內角度數總和一定等於 180 度。

is 才對. be equal to (等於) 不是 have equal to

可以參考底下網路現行用法( the sum of the angles is ....)

Since the sum of the angles in a triangle is 180º, the sum of the angles in the quadrilateral is 360º because it is composed of two triangles.

2. Because of protective laws and captive breeding efforts in both the United States and China, the number of cranes is slowly but steadily increasing. 鶴鳥的數目正緩緩穩定增加

這兩題的主詞 the sum, the number 都是單數名詞，所以be 動詞用 is.

• sum:

ex. The sum of 7 and 12 is 19. ( 7加12的和是19。)

原則上 the sum of 是後接單數動詞

In plane gemetry, the sum of the internal angles of any triangle

have always equal to 180 degrees. <--為何是複數，參閱下述解釋。

number:

1. a number of 作"若干 ，一些"解時，後接名詞複數，動詞亦用複數。

ex: A number of books are missing. (一些書不見了。)2、 the number of 後接名詞複數，動詞用單數。

ex. The number of cars is increasing. (汽車的數量在增加。)

出處: 字典文法【note】

(1) number 一字作為主詞，其動詞應用單數或複數，用法不一，

例如:

The unmber of students is icreasing. ( 學生的數目在增加。)

在這句裏 number 是一個集體的數目，當然用單數動詞。

但是在這一句裡:

A number of students {is/are} absent today.

(有一些學生今日缺席) 便很有問題。

大概舊式的語法用 is , 較新的語法向於 are ，我們如果 承認 a number of = some,

那麼用複數的動詞似較合理。(2) number , sum 意思都是兩個以上之人或物加在一起之總數。

number---指把一群或一組之人或物計算後所得之總數:

Only twelve came ----a smaller number than usual.

(只來了十二位。)----較平常為少的數目。sum ---指數字或東西相加所得之總數:

The sum of two and two is four.(二加二之和為四。)參閱: 遠東英漢大辭典 page 1425

Source(s): dictionary / grammar