"I need to know complicated vocabulary for when I read CNN news or English language newspapers."
"I need to know complicated vocabulary for when I read CNN news or English language newspapers."
"I need to know ~" 「〜を知るが必要です」
"complicated vocabulary" 「難しい単語」"difficult words" も使えます。
"for when~" 「〜時に」
"I read CNN news or English language newspapers" 「CNNニュースや英字新聞を読む」
"I don't think I need complicated vocabulary for every day conversations but I need it for when I read CNN news or English language newspapers."
「日常英会話においては難しい単語を使う必要はないと思うけど、CNNニュースや英字新聞を読む時に必要です」
You need to know a broad range of vocabulary to be able to read CNN news or other English newspapers.
ーYou don't need to know difficult words to get by in daily English, but you need to know a broad range of vocabulary to be able to read CNN news or other English newspapers.
「難しい単語を知らなくても日常英会話でなんとかやっていけるが、CNNニュースや英字新聞を読めるためには幅広い単語を知る必要がある」
to get by で「なんとかやっていく・なんとか通用する」
a broad range of vocabulary で「幅広い単語・語彙」
ご参考まで！
オーストラリア 
カナダ 
