こんにちは。
I have work on Saturday too.
土曜日も仕事がある。
I'm working on Saturday as well.
土曜日も働きます。
上記のような言い方ができます。work は have work（名詞）で「仕事がある」、work（動詞）で「働く」という意味です。「も」は too でも as well でも同じです。as well の方が少し丁寧な感じがします。
ぜひ参考にしてください。
Any of these statements can describe this situation.
1. I have to work on Saturdays as well.
私は土曜日にも仕事をしなければなりません。
2. I only have Sunday off this week.
今週は日曜日だけ休みます。
どちらの例文も質問者様のいう状況で使用できます。
1. I have to work on Saturdays as well.
（私は土曜日にも仕事をしなければなりません）
2. I only have Sunday off this week.
（今週は日曜日だけ休みます）
*I will be working on Saturday too-Some people don't work Saturdays and others do. If need be for a person who is normally off on Saturdays to work, then they have to.
Example Sentences:
I think this Saturday i will go to work because we are preparing end of year financial reports.
I have a lot of work to do, I think on Saturday I will working too.
*I will be working on Saturday too
（土曜日も仕事です）
-土曜日に働く人もいれば、お休みの人もいますよね。
必要があれば、通常土曜日はお休みの人も働かなくてはいけない時もあります。
【例文】
I think this Saturday I will go to work because we are preparing end of year financial reports.
（年度末会計報告書を作成しなくてはならないから、今週の土曜日は会社に行かなければなりません）
I have a lot of work to do, I think on Saturday I will working too.
（仕事が沢山あるから、土曜日も働かなくてはいけないと思います）
Overtime = time worked in addition to one's normal working hours.
"There are fewer opportunities for overtime these days."
A day off = a day's holiday from work or school, on what would normally be a working day.
"It's her day off today."
Due to =because of; owing to.
"He had to withdraw due to a knee injury"
・Overtime = 通常の就業時間に加えて働く時間
"There are fewer opportunities for overtime these days."
（最近は残業する機会が減った）
・A day off = 通常は学校や仕事があるけれど、学校や仕事がない日
"It's her day off today."
（今日彼女のお休みです）
・Due to =によって
"He had to withdraw due to a knee injury"
（彼は膝の怪我で退場しなければならなかった）
I am so busy recently i have been working through the weekend
I work on Saturday, I have been really busy lately
I am working on Saturday's , it's been so busy.
examples
"i have been snowed under recently,
so i work Saturday's too".
or
"i work over the weekend, it is so busy at the minute.
or
"i have been working all week because
it is so busy and most weekends".
or
"I work loads at the minute, i am just so busy"
例
"I have been snowed under recently, so I work Saturday's too".
（最近とても忙しいので土曜日も働きます。）
あるいは
"I work over the weekend, it is so busy at the minute.
（私は週末も働きます。今とても忙しかったので。）
あるいは
"I have been working all week because it is so busy and most weekends".
（とても忙しかったので、週中ずっとと週末殆ど働きました。）
"I work loads at the minute, I am just so busy"
（いま、仕事が沢山あり、本当に忙しいです。）
I have to work on Saturday because work has been really busy.
I have to work on Saturday because I have been tied up at the office.
I have to work on Saturday because it is keeping me preoccupied.
I have to work on Saturday because work has been really busy.
'Because it has been really busy' = Because is the beginning of explaining the reason for your first statement.
It/ Work = are the subject of the sentence.
I have to work on Saturday because <I have been tied up at the office>.= I have been busy at the office.
Tied up= to be kept busy with some activity.
Example: I was tied up with completing the reports on Saturday.
I have to work on Saturday because it is keeping me preoccupied.
Preoccupied (verb)= to be kept busy with something
Example: I was preoccupied with my son because of his sports game.= I was busy with my son because of his sports game.
"I have to work on Saturday because work has been really busy."
（土曜日も働かなければなりません。なぜなら仕事が本当に忙しいからです。）
'Because it has been really busy'
= "Because" は理由を説明するにあたって最初に述べる言葉です。
It/ Work = 文の主語となります。
"I have to work on Saturday because <I have been tied up at the office>."
（土曜日も働かなければなりません。オフィスから離れられないからです。）
= 私はオフィスでとても忙しくしています。
Tied up= ある行動によって忙しいことを意味します。
例: I was tied up with completing the reports on Saturday.
（土曜日はレポートを作成するためにとても忙しくしていました。）
"I have to work on Saturday because it is keeping me preoccupied."
(土曜日も働かなければなりません。なぜならとても忙しいからです)
Preoccupied (動詞)= 何かで忙しくしていることを意味します。
例: I was preoccupied with my son because of his sports game.
（私の息子のスポーツの試合があったので忙しかったです。）
= I was busy with my son because of his sports game.
（私の息子の試合のため忙しくしていました。）
I need to do some overtime & start working on Saturdays too, I am so busy lately...
When we work more than our scheduled hours...this is called working "overtime"
"I need to do some overtime & start working on Saturdays too, I am so busy lately..."
シフトよりも多く働くことを、 "work overtime"（残業する）と言います。
"I need to do some overtime & start working on Saturdays too, I am so busy lately..."
残業して、土曜日も働かないといけない。ここ最近すごく忙しい。
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