Replacing になっている with だ


A sentence from JapanesePod 101:

> 米は、多くの食事で、重要な糖質源になっている。  
>  Rice is an important source of carbohydrates in many diets.

The になっている seems unnecessary here. Could one simply end the sentence with 糖質源だ
without changing the meaning? i.e.

> 米は、多くの食事で、重要な糖質源だ。




You can replace '糖質源だ' with '糖質源になっている' without changing the meaning of the
original sentence.

As Mobius Pizza is saying, sometimes '糖質源だ/糖質源である' are used instead of
'になっている'. Meanwhile, '糖質源です' and '糖質源になっている' are also objective and assertive
expressions. Examples of subjective expressions are '糖質源だろう/糖質源でしょう'.

The 'has become...' sentence in Sjiveru's comment refers to the role of the
rice in the past. But the original sentence only mentions the present state.
The sentence in Sjiveru's comment

[code]

    Rice has become an important source of carbohydrates in many diets
    
[/code]

translates to, say,

[code]

    '米は、多くの食事で、重要な 糖質源となった/糖質源となってきた'
    
[/code]

As to PhoenixFox's comment, '糖質源になっている' and '糖質源だ' are both direct
expressions. While the original sentence means 'It is 'usually' the case
that...', the meaning 'usually' comes from '多くの食事で' (in many diets). If you
say, omitting 'in many diets',

[code]

    米は、重要な糖質源になっている。
    
[/code]

this is equal to saying

[code]

    米は、重要な糖質源だ。
    
[/code]

Therefore, you can replace '糖質源になっている' with '糖質源だ'.

However, as mentioned in the comments, 'になっている' seems to be more frequently
used than 'だ'. The reason is unclear to me, but there is a similar, widely-
used expression '...源になっている/...源になる'. Also, the author might prefer the rhythm
(ending always with 'だ' makes sentences too short and monotonic).




You can replace '糖質源だ' with '糖質源になっている' without changing the meaning of the
original sentence.

As Mobius Pizza is saying, sometimes '糖質源だ/糖質源である' are used instead of
'になっている'. Meanwhile, '糖質源です' and '糖質源になっている' are also objective and assertive
expressions. Examples of subjective expressions are '糖質源だろう/糖質源でしょう'.

The 'has become...' sentence in Sjiveru's comment refers to the role of the
rice in the past. But the original sentence only mentions the present state.
The sentence in Sjiveru's comment

[code]

    Rice has become an important source of carbohydrates in many diets
    
[/code]

translates to, say,

[code]

    '米は、多くの食事で、重要な 糖質源となった/糖質源となってきた'
    
[/code]

As to PhoenixFox's comment, '糖質源になっている' and '糖質源だ' are both direct
expressions. While the original sentence means 'It is 'usually' the case
that...', the meaning 'usually' comes from '多くの食事で' (in many diets). If you
say, omitting 'in many diets',

[code]

    米は、重要な糖質源になっている。
    
[/code]

this is equal to saying

[code]

    米は、重要な糖質源だ。
    
[/code]

Therefore, you can replace '糖質源になっている' with '糖質源だ'.

However, as mentioned in the comments, 'になっている' seems to be more frequently
used than 'だ'. The reason is unclear to me, but there is a similar, widely-
used expression '...源になっている/...源になる'. Also, the author might prefer the rhythm
(ending always with 'だ' makes sentences too short and monotonic).

