have（例文では過去分詞had）も文脈上「食べる」の意味で用いることができます。
I haven't had anything today.
I've had nothing today.
「今日は何も食べてないんだ」
todayの代わりにsince this morning「朝から」をつけてもいいですね。
また、飲み物は飲んだけれど固形物は食べていないという状況は、
I haven't had any solid food today, just drinks.と表現できます。
ご参考になれば幸いです。
例題2文とも｢今朝から何もたべていない｣という意味です。
have + eaten で食べている
これにnothingをつけると｢何も食べていない｣
have not eaten で食べていない
これにanythingをつけると｢何も食べていない｣
ちなみに、｢昨日の朝から｣の場合は、
since this morningがsince yesterday morningになります。
Your plan is to lose 3 Kgs in one week! The first two days of your diet went well, but the third day you gave in to your appetite and stopped off at McDonald's. Today you decided to fast and only drink water. You meet a friend on the way home who invites you to go to a restaurant. You explain:
"I haven't eaten all day. I'm starving, but I want to only drink water today. Maybe next week!"
【背景】
あなたは1週間で3Kgs落とす計画しています。ダイエットの最初の2日間は上手くいきましたが、3日目は食欲に負けてマクドナルドに立ち寄りました。今日は何も食べず水しか飲まないことに決めました。家に帰る途中で友達に会い、レストランに誘われました。そこであなたは説明します:
"I haven't eaten all day. I'm starving, but I want to only drink water today. Maybe next week!"
（一日何も食べていなくてお腹ぺこぺこだけど、今日は水しか飲みたくないんだ。来週でもいいかな？）
Any of these statements are suitable :
1. I haven't eaten anything all day.
2. I haven't eaten anything today.
Both these statements means that you have not eaten anything for the whole day today.
ご紹介した例文はいずれも適切です。
1. I haven't eaten anything all day.
2. I haven't eaten anything today.
どちらの表現も、あなたが今日一日何も食べていないことを意味します。
I am so hungry because of not eating since morning.
I have not eaten a thing since morning.
Can you believe it? I have eaten nothing since morning.
The result of not having eaten since morning is definitely being very hungry. The adjective 'hungry' has several meanings, but, in this context, it means 'feeling or showing the need for food'. The adverb 'so' has several meanings, but, in this context, it means 'to such a great extent'.
So, you may say:
I am so hungry because of not eating since morning.
In the second sentence, you have said it succinctly (clearly and short) as follows:
I have not eaten a thing since morning.
In the third line, you started by exclaiming: Can you believe it?! This is because it is rare for someone not to have eaten anything for the whole day.
So, you may say:
Can you believe it? I have eaten nothing since morning.
朝から何も食べていないと、間違いなくとてもお腹が空いているでしょうね。形容詞の'hungry'には色んな意味がありますが、今回の文脈では、「食べ物の必要性を感じている、表している」という意味です。副詞の'so'には色んな意味がありますが、今回の文脈では、「とても」という意味です。
そのため、以下のように言うといいでしょう。
I am so hungry because of not eating since morning.
（私は朝から何も食べてないせいで、とてもお腹が空いている。）
2番目の文では、以下のように簡潔に（明らかに、短く）表現しています。
I have not eaten a thing since morning.
（私は朝からひとつも食べてない。）
3番目の文では、Can you believe it?!という文で大袈裟に始めています。一日中何も食べていないというのは珍しいことなので、このように表現しています。
そのため、以下のように言うといいでしょう。
Can you believe it? I have eaten nothing since morning.
（信じられる？私朝から何も食べてないんだよ。）
If you have not eaten the whole day since morning and you would like to tell someone this, you can say something like "I have not eaten anything the whole day today." or I haven't eaten anything since this morning.". Both of these sentences mean the same thing and are polite ways to say this.
「朝から何も食べていない」は、次のように言えます。
"I have not eaten anything the whole day today."（今日は一日何も食べていない）
"I haven't eaten anything since this morning."（朝から何も食べていない）
これらはどちらも同じ意味です、丁寧な言い方です。
おっしゃられている内容は、以下のようにも表現できると思いました(*^_^*)
I haven't eaten anything since this morning.
「今朝から何も食べていない」
I haven't eaten anything today.
「今日は何も食べてない」
以上です。
少しでも参考になれば幸いです(*^_^*)
I am so hungry, I have not eaten since this morning.
▪My last meal was last night
>This is indicating that the last time you had something to eat was last night
............●............
▪I am so hungry, I have not eaten anything today
>This means that you are hungry because you had nothing to eat during the day
▪My last meal was last night
最後に何かを食べたのが昨晩だということを表しています。
▪I am so hungry, I have not eaten anything today
日中何も食べていないのでお腹がすいたという意味です。
Very similar sentences with a small difference. The second sentence use the word "thing" but basically they are the same, so feel free to use both of them.
Both of these mean the same thing which means you have consumed zero food all day but can sometimes mean that you are very hungry because you have hardly eaten any food all day.
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