Native English speakers speak so fast and abbreviate words so I can't catch what they are saying.
Native English is so fast it's difficult for me to catch all the words.
Native English speakers speak too quickly for me to catch what they say.
「ネイティブの英語は速くて短縮されてて聞き取れない」＝ Native English speakers speak so fast and abbreviate words so I can't catch what they are saying. / Native English is so fast it's difficult for me to catch all the words. / Native English speakers speak too quickly for me to catch what they say.
ボキャブラリー
native English speaker ＝ ネイティブ
speak ＝ 話す・喋る
so fast ＝ とても速い
abbreviate words ＝ 短縮
can't catch what they are saying ＝ 言っている事を聞き取れない
difficult for me ＝ 私には難しい
too quickly ＝ 速すぎて
「ネイティブの人が私の英語のどのへんが分からないのか気を使ってくれなくて」＝ Native speakers often don't think about how much I understand and don't slow down their speech for me.
Native English is fast and abbreviated, so it's hard to catch.
「ネイティブの英語は速くて短縮されてて聞き取れない」という表現は英語で "Native English is fast and abbreviated, so it's hard to catch." と言えます。「native English」は「ネイティブの英語」、「fast」は「速い」、「abbreviated」は「短縮された」、「hard to catch」は「聞き取れない」という意味です。
例えば、さらに詳細に伝えたい場合は： "Native speakers talk so fast and abbreviate words, so I can't understand them." 「ネイティブの人たちはとても速く話し、言葉を短縮するので、私には理解できない。」
または： "When native speakers talk, it's so fast and they use contractions, so it's hard for me to follow." 「ネイティブの人が話すときはとても速くて、短縮形を使うので、ついていくのが難しい。」
イギリス 
アメリカ合衆国 
