Poor Silva lay on his bed all this time, suffering much from his wounds, while Mr McRitchie, when he could leave his side, went off with his gun to explore the island, and to search for specimens of its natural history. (A Voyage round the World by W.H.G. Kingston）
動画の後半部分でリスニング用音声が流れます。
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。
Poor Silva lay on his bed all this time,／（現在分詞の前）suffering much from his wounds,／（接続詞の前）while Mr McRitchie, when he could leave his side,／（コンマの後）went off with his gun to explore the island,／（接続詞の前）and to search for specimens of its natural history.
語句のかたまりを前から訳していきます。
Poor Silva lay on his bed all this time,
かわいそうなシルバは、ずっとベッドに横たわっていた
suffering much from his wounds,
傷のせいで大いに苦しみながら
while Mr McRitchie, when he could leave his side,
一方、マクリッチー氏は、シルバのそばを離れられるときは
went off with his gun to explore the island,
銃を持って、島を探検するために出かけた
and to search for specimens of its natural history.
そして、島の自然史の標本を探すために
Poor Silva lay on his bed all this time, suffering much from his wounds, while Mr McRitchie, when he could leave his side, went off with his gun to explore the island, and to search for specimens of its natural history.
suffering much from his wounds→ 付帯状況の分詞構文です。「〜ながら」と訳せます。suffer from〜 = 〜で苦しむ
went off with his gun→ with〜 = 〜を持って、〜を携帯して
かわいそうなシルバは傷のせいで大いに苦しみながら、ずっとベッドに横たわっていた。一方、マクリッチー氏は、シルバのそばを離れられるときは、島を探検するため、そして島の自然史の標本を探すために銃を持って出かけた。
今回の課題文には、ペアになっている不定詞があります。
to explore the island
went off with his gun＜and
to search for specimens of its natural history
「銃を持って出かけた」目的は２つあるわけです。後ろの方の to を切り離してしまうと、意味がとれなくなります。
