さぞ

surely, certainly

adverb Uncommon #19,285
surely, certainly Often used with ことだろう/でしょう to express strong empathy or an inference about someone's feelings or situation: “it must be...”
JA: ご家族はさぞ心配したことでしょう。
EN: Your family must have been very worried.

もし彼が死んだらさぞ悲しむだろう

I would be terribly sad if he died.

さぞ見ものでしょうね.

It must be quite a sight.

— もののけ姫 (1997)

俺を捕まえてさぞいい気分だろうな

You must feel pretty good about catching me.

— TAXi (1998)

トムゲーム使ってる時間にさぞ驚くだろう

You'd be surprised how much time Tom spends playing games.

さぞショックだったでしょう

That must have been quite a shock.

明日の朝パパはバルトロメオ手を洗うさぞきれいになるだろうな

Tomorrow morning, Dad will wash his hands with Bartolomeo. They’ll get really clean, I bet.

— ライフ・イズ・ビューティフル (1997)

さぞ私に腹を立ててるだろうね

You must be really mad at me, huh?

— フィフス・エレメント (1997)

さぞ辛かったでしょうそうね

That must have been really tough. Yeah.

— レベッカ (1940)

あのご婦人戻ったらさぞ驚くだろう

That lady will be mighty surprised when she comes back.

— ウエスタン (1968)

シャイアさぞ素晴らしいだろうなギャムジー殿

The Shire must be a truly wonderful place, Master Gamgee...

— ロード・オブ・ザ・リング/二つの塔 (2002)

さぞマグダ悲しむわね

Magda must be very sad.

— ダーク・プレイス (2015)