of the essence

time is of the essence. 時間が何よりも大切な要素だ。of the essence がイディオム部分です。0;01 when money is no object and time is of the essence, those who could afford the finest are shunning the hassles of public travel. 金が問題ではなく時間が問題なとき、金持ち庶民の移動手段を敬遠する。

https://www.youtube.com/watch?v=b1OFJRm-PFE  0:14 time has been of the essence here because the forecast shows warmer temperatures are coming. 暖かくなり（雪が解けて洪水の恐れがあるため）除雪作業は一刻の猶予も許されない。= 時間との戦いだ。
https://www.youtube.com/watch?v=ObGE1Eh8FhE  5:25 time is of the essence. ティオさんにとっては残された時間はいくばくもない。

練習問題解答
a-817 of the essence
a-995 of the essence
a-3224 of the essence
a-5679 time is of the essence
a-8014 time and quality were of the essence
a-9624 time is of the essence
b-0233 time is of the essence
b-4975 time is of the essence
b-5383-a time is of the essence