He made the excuse of being busy and assigned all of his tasks to his subordinates.
ご質問ありがとうございます。
・「He made the excuse of being busy and assigned all of his tasks to his subordinates.」
（意味)彼は忙しいことを[言い訳](https://eikaiwa.dmm.com/uknow/questions/41867/)に、自分の仕事を部下に押し付けた。
<例文> I heard he's a horrible boss. He made the excuse of being busy and assigned all of his tasks to his subordinates.
<訳> 彼は最悪な上司です。彼は忙しいことを言い訳に、自分の仕事を部下に押し付けた。
参考になれば幸いです。
He passed off some of his work to the guy below him alleging that he was busy.
この場合、次のような言い方ができますよ。
ーHe passed off some of his work to the guy below him alleging that he was busy.
「彼は忙しいことを言い訳に、部下に彼の仕事を押し付けた」
to pass off some of one's work 「仕事を回す」
guy below him「彼の部下」
alleging ... で「…を（口実や言い訳と）主張する」
ご参考まで！
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