down pat

リーダーズダイジェスト８月号に50年前に起きたイギリスの列車強盗の記事があり、下はその一部の抜粋です。
The signals and emergency telephone were observed, and an expert electrician, another ex-con, was added to the group. Some of the gang strolled in to Euston Station in London, and quietly watched railroad men uncoupling cars. To be sure that they had the procedure down pat, they filmed the action with a movie camera.
"down pat" は初めて見る表現だと思います。　辞書で意味を調べます。
・Wiktionary: (idiomatic) Thoroughly practiced, rehearsed, or understood.
・Dictionary.com: down cold / pat, mastered or learned perfectly: Another hour of studying and I'll have the math lesson down cold.
・Urban Dictionary: at the point of having something memorized or perfected.: I practiced that guitar riff for days till I got it down pat.
この "down pat" の "pat" は以前採り上げた "pat"、"exactly suited to the occasion" ("A pat reply") と少し共通点があるような、ないような。

jump start

A man tries to get into a nightclub with no tie on. The bouncer outside says he has to have a tie, so the man goes back to his car and gets a pair of jump leads and puts them around his neck. He returns to the bouncer and asks if he can come in now. The bouncer says, "Yeah, but don't start anything."
大分昔の話ですが、初めてハワイに行った時に、レストランで入場を断られたことがあります。短パンだったのでそのせいかと思いましたが、理由を聞くと、短パンはＯＫだがビーチサンダルは駄目だと言われました。

sibling rivalry

Reader's Digest 8月号の記事The Hunger Gamesの個所はとても視覚的で、良く分かります。
Food's central role in sibling rivalry is, in part, a matter of biology. The pancake-night melee at the Joyces was triggered by the same instinct that drives piglets to fight for position nearest the sow's head, where the nipples deliver the most milk.
Spotted hyenas attack a younger sibling within minutes of its birth in order to minimise competition for their mother's milk.
これは一人っ子だった人には分からないでしょうね。

apoplectic

Reader's Digest 8月号の記事The Hunger Gamesは、兄弟（姉妹）のある人は子供の頃に誰でも経験したはずです。
Nothing triggers sibling rivalry like the dinner table. It took only four decades for my family to get over it
今日採り上げたい単語は次ぎの個所にありました。
Of the countless fist fights between Joe Kennedy Jr and his kid brother Jack, one of the most memorable was triggered when Jack snatched Joe's slice of chocolate pie - his brother's favourite dessert - from under Joe's nose at the dinner table. Gobbling it up, Jack ran outside and down the beach, his apoplectic brother giving chase.
"apoplectic" の意味を辞書で調べます。
・Merriam-Webster's Online Dictionary: greatly excited or angered: was apoplectic over the news
・Cambridge English Dictionary: extremely and obviously angry: He was apoplectic with rage/ fury
. 良く考えたら "apoplexy" から出た言葉ですね。・WordNet: pertaining to or characteristic of apoplexy ("Apoplectic seizure")

opening bars

Reader's Digest 8月号のSmart Animalsの記事に出てきた表現です。
My cockatiel, Dachi, was one of a kind. I taught him to sing "For He's a Jolly Good Fellow" and "Happy Birthday", but his favourite was the opening bars of Mozart's Clarinet Concerto.
"opening bars" の表現ですが、多分最初の小節のことであろうと推測しました。辞書で確認します。
・Vocabulary.com: musical notation for a repeating pattern of musical beats: “the orchestra omitted the last twelve bars of the song”
・Cambridge English Dictionary: one of the small equal parts into which a piece of music is divided, containing a fixed number of beats: Waltzes have three beats in/to the bar (= in each bar ).
音楽用語で私の知っているその他の単語は "score" と "note" 位でしょうか。

gut flora

Reader's Digest 8月号の記事 "A Day in the Life of Your Gut" からの抜粋です。.
Even better, the yoghurt is teeming with probiotics - live bacterial critters that help maintain my gut flora (GF), the amazing microbes inside me that help with digestion and immunity..
"flora" と言うと "flora and fauna" で覚えた植物相の意味を最初に思い浮かべるのですが、ここでの "gut flora" の意味は直後に "microbes inside me (gut) that help with digestion and immunity" と説明があるので辞書を見なくても植物相の意味で使われていないことが分かります。　一応辞書で確認します。
・Wiktionary: The microorganisms that inhabit some part of the body, such as intestinal flora
ちなみに私は毎朝自家製のヨーグルトを食べています。

Doubling back

ボストンマラソンで爆弾をしかけた犯人の二人が逃走中にCARJACKをした時の記事（Reader's Digest 8月号）から引用します。
The tank nearly empty, they stopped at a gas station, but the pumps were closed.
Doubling back, they returned to Watertown and grabbed a few more things from the parked car, but nothing from the trunk.
"Doubling back" はその後に "they returned" とあるのと意味は結局同じ気がしますが、この表現を見るのは初めてなので辞書を見ます。
・Collins Dictionary: to go back in the opposite direction (esp in the phrase double back on one's tracks): But he couldn't double back the way he'd come for fear of running into the army patrol.
・Merriam-Webster's Online Dictionary: to turn and go back in the direction you have come from: We realized we had taken the wrong road and had to double back.
・Vocabulary.com: retrace one's course: Others turned sharply as they exited, then doubled back to reconsider.
元来た同じ道を戻る感じですね。やはり、"return" と一緒に使うのは冗長表現の気がします。

Impatient

I called a patient to confirm an appointment with the doctor I work for, and her husband answered.
"Hello, may I speak with Anna?" I asked.
"Who?" he said.
"Annna."
"Santa?"
"No, Anna."
"Who is this?"
"This is the doctor's office calling for Anna."
"Who?"
"The doctor's office calling to speak with Anna!"
"Oh, Anna," he said. "You'd better talk to me; Anna is hard of hearing."

Robert E. Lee

Any fool can try to defend his or her mistakes--and most fools do--but it raises one above the herd and gives one a feeling of nobility and exultation to admit one's mistakes.
For example, one of the most beautiful things that history records about Robert E. Lee is the way he blamed himself and only himself for the failure of Pickett's charge at Gettysburg.
(Excerpt from How to Win Friends and Influence People)

lapdog

Sept.1, 2013 のJapan Times Onlineにあった記事タイトルです。
With vote, U.K. sheds image as U.S. lapdog
LONDON ? Lap dogs no more!
"lapdog" がどんな犬かは知りませんが（もちろん膝に乗るような小さな犬だと想像はできます）、上での意味は「言いなりになる人/国」の意味で使われているに違いありません。記事の中では "poodle" も出てきます。 After the British Parliament’s decision to reject taking part in any U.S.-led strike against the regime of Syrian President Bashar Assad, that victory cry rang out Friday from many quarters of the nation. For those who smarted at the memory of former Prime Minister Tony Blair ? lampooned in the press as President George W. Bush’s “poodle” ? Friday marked the first day of a sweet new independence.
"lapdog" を辞書で確認します。
・Collins Dictionary: a person who attaches himself to someone in admiration or infatuation: 'Blair is like a little lapdog ', said Ken Livingstone, to rapturous applause.
・Cambridge English Dictionary: someone who is willing to do anything that a more important person tells them to do: Opposition parties accuse the newspaper's editor of being a government lapdog.