Her companions must have been very hard of hearing, for it was not until she had slid two-thirds of the way down that any of them seemed to attend to her, and then the whole party set off rushing down the hill-side, at the bottom of which they stood ready to receive her.（A Yacht Voyage Round England by W.H.G. Kingston）注：she が悲鳴をあげながら、丘の斜面を滑り落ちている場面です。
英文を前から読んでいくために、語句のかたまりを作ります。こんな具合に課題文をスラッシュ（斜め線）で区切ります（スラッシュリーディング）。語句のかたまりを意識すると、リスニングで英語の意味をつかむのが楽になります。
Her companions must have been very hard of hearing,／（接続詞の前）for it was not until she had slid two-thirds of the way down／（接続詞の前）that any of them seemed to attend to her,／（接続詞の前）and then the whole party set off rushing down the hill-side,／（前置詞の前）at the bottom of which they stood ready to receive her.
語句のかたまりを前から訳していきます。
Her companions must have been very hard of hearing,
彼女の仲間たちは、とても耳が遠かったに違いない
for it was not until she had slid two-thirds of the way down
というのは、彼女が斜面の３分の２を滑り落ちて初めて
that any of them seemed to attend to her,
彼女に注意が向けられたようだったからだ
and then the whole party set off rushing down the hill-side,
そして、仲間たち全員が斜面を駆け下りはじめた
at the bottom of which they stood ready to receive her.
そして、丘のふもとで彼女を受け止める態勢を整えた
彼女の仲間たちは、とても耳が遠かったに違いない。というのは、彼女が斜面の３分の２を滑り落ちて初めて、彼女に注意が向けられたようだったからだ。そして、仲間たち全員が斜面を駆け下りはじめ、丘のふもとで彼女を受け止める態勢を整えた。
Her companions must have been very hard of hearing, for it was not until she had slid two-thirds of the way down that any of them seemed to attend to her, and then the whole party set off rushing down the hill-side, at the bottom of which they stood ready to receive her.
Her companions must have been very hard of hearing→ must have〜 =「〜したに違いない」（must〜 =「〜に違いない」）
it was not until she had slid two-thirds of the way down that〜→ it was not until〜that― =「〜して初めて、―した」
at the bottom of which they stood ready to receive her→ whichの先行詞は the hill-side です。at the bottom of the hill-side =「丘のふもとで」
動画の後半部分でリスニング用音声が流れます。
