A glimpse at the “private, hidden face” of Albert Einstein, including the celebrated scientist's thoughts on everything from his fears     1     his best work was behind him to his beloved younger sister, Maja.

The collection, which includes a previously unknown photograph of Einstein as a five-year-old and the only     2     （survive）letter written by Einstein to his father, comes from the archive（档案）of Maja Winterler-Einstein and her husband Paul Winteler. A mix of letters, postcards and photographs, many of     3     have not previously been published, range in date from 1897 to 1951.

“What is remarkable about them comes from the fact that he had this incredibly close relationship with his sister. It's quite clear that     4     he's writing to her, there's no role-playing at all.” said Thomas Venning at Christie's. which will auction（拍卖）the letters soon. “He was very conscious of what     5     （expect）of him after he became famous, and you don't get any of that in letters to his sister. He says some things that I've never seen him say anywhere else. and I've catalogued many hundreds of his letters.”

In 1924, nine years after he completed the general theory of relativity in 1915. Einstein would write to Maja that “scientifically I haven't achieved much recently-the brain gradually goes oft （停止）     6     age, though that is not so unpleasant. It also means that you're not so answerable for your later years.” Ten years later, he would write to her: “I am happy in my work,     7     in this and in other matters I am starting to feel that the brilliance of younger years is past.”

Venning said he had not seen Einstein     8     （admit）this anywhere else. “It's not him     9     （play）a role: you can see that thought going through his head, which is true-if Einstein had died in 1916, his fiundamental legacy would have been complete. He carried on working for another 40 years without making any other great breakthrough, so it's just an extraordinary moment which we get because of     10     close their relationship was. He didn't have to reassure（使安心）her,” he said.

2 . Zelda Fitzgerald, as is revealed by numerous personal books and letters, wore many labels in her life. She was “the original flapper girl” and “the spirit of the Jazz Age.” Married to the celebrated writer F. Scott Fitzgerald (author of The Gireat Giatsby), she was by turns his muse and the woman who ruined his life. In her later years she was “Crazy Zelda”.

Accurate as all these descriptions may be, they do not tell the whole story. Born in Montgomery, Alabama, she was noted for her beauty and high spirits in dancing. In July 1918, at a country club dance, Fitzgerald was hooked immediately by the beautiful and charming 18-year-old Zelda who out-shined(使逊色)other beauties with her distinguished ballet. A light affection evolved into a lengthy long-distance pursuit of weekly letters, with Fitzgerald aware of her uncommitted dating of other men. He courted her after his discharge from the Army in February 1919, but Zelda had doubts. Her fiance wasn't rich and there was no guarantee he’d ever be famous. His short stories didn’t sell. His apartment was a dump. Zelda gave back the ring. Hoping to fix the “no money” part of his problem. Fitzgerald quit the job and started to rewrite novels for success and money so that he could win back his girl. Finally, he made it! On March 20, 1920, his novel This Side of Paradise got published and Zelda agreed to marry him.

However, their marriage was troubled by wild drinking, fighting, infidelity(不忠实)and bitter recriminations. Emest Hemingway, whom Zelda disliked, blamed her for Scot’s declining literary output, though she has also been portrayed as the victim of an overbearing husbano Actually. Zelda was also creative, pursuing both dancing and writing. Some scholars have portrayed Zelda as a creative talent ignored by the patriarchal(男权的)society of the day. Her inspiration was even drawn by her husband in literary creation-Scott used their relationship as material in his novels, even borrowing episodes from Zelda’s diary and applying them into his fictional writings. She detested(讨厌)her husband’s practice: “Mr. Fitzgerald-I believe that is how he spells his name-seems to believe that plagiarism begins at home.” To seek an artistic identity of her own value, as she put it “I wish I could write a beautiful book to break those hearts that are soon to cease to exist.”

Nevertheless her unique personality was starting to seem more unbalanced than charming. The couple-like the rest of the nation-was living on borrowed time. In October 1929 the stock market crashed, triggering the Great Depression. Six months later, Zelda suffered her first nervous breakdown. After being diagnosed with schizophrenia（精神分裂), she was increasingly confined to specialist clinics, and since then has departed with her husband. Zelda died later in a fire at her hospital in Asheville, North Carolina, putting an end to her flamboyant(绚丽夺目的)life. A young woman, especially one in the 1920s, who was against traditional dress and behavior.

It was nearing midnight and the Prime Minister was sitting alone in his office, reading a long memo that was slipping through his brain without leaving     1     (slight) trace of meaning behind.

He was waiting for a call from the President of a far distant country, and     2     wondering when he would telephone and trying to put down unpleasant memories of what had been a very long, tiring, and difficult week, there was not much space in his head for     3     else. The more heat tempted to focus on the print on the page before him, the more clearly the Prime Minister could see the gloating(幸灾乐祸的) face of one of his political opponents.

This particular opponent had appeared on the news that very day, not only to list all the terrible things that had happened in the last week (as though anyone needed reminding)     4     to explain why each and every one of them was the government's fault.

The Prime Minister's pulse quickened     5     he thought of these accusations, for they were neither fair nor true. How on earth was his government supposed to have. stopped that bridge     6     (collapse)? It was outrageous for anybody to suggest that they were not spending enough on bridges. The bridge was fewer than ten years old, and the best experts were at a loss to explain     7     it had snapped cleanly in two, sending a dozen cars into the watery depths of the river below. And how dare anyone suggest that it was lack of policemen     8     had resulted in those two very nasty and well—publicized murders? Or that the government       9     have somehow foreseen the freak hurricane in the West Country that had caused so much damage to both people and property? And was it his fault that one of his Junior Ministers, Herbert Chorley, had chosen this week to act so peculiarly     10     he was now going to be spending a lot more time with his family?

5 . Most animal species in the world have developed some sort of natural camouflage that helps them find food and avoid attack. The specific nature of this camouflage varies considerably from species to species.

Camouflage develops differently depending on the physiology and behavior of an animal.    1    

An animal's environment is often the most important factor in what the camouflage looks like. The simplest camouflage technique is for an animal to match the "background" of its surroundings.

Since the ultimate goal of camouflage is to hide from other animals, the physiology and behavior of an animal's predators or prey is highly significant.     2    . For example, there’s no point in an animal replicating the color of its surroundings if is main predator is color-blind.

In addition to background-matching coloration, many animals have distinctive designs on their bodies that serve to conceal them. These designs, which might be spots, stripes or a group of patches, can help the animal in a couple of ways. First, they may match the pattern of "the model", the background of the animal's surroundings. Second, they may serve as visual disruptions. Usually, the patterns are positioned out-of-line with the body's contours (外形).     3    . This makes it hard for the predator to get a clear sense of where the animal begins and ends — the pattern on the body seems to nun of in every direction.

Other animals use a more aggressive sort of mimicry. Several moth species have developed striking designs on their wings that resemble the eyes of a larger animal. The back of the hawk moth caterpillar actually looks like a snake head, a frightening visage for most predators he moth would come across.

Mimicry is a different approach than ordinary camouflage, but it works toward the same end. By developing a certain appearance, an animal species makes itself a harder target for predators and a sneakier hunter for prey. As animal species evolve, they become more and more in tune with their environment.     4    . After all, being entirely overlooked by a predator is preferable to having to put up a fight.

6 . A breed of upstart apps is taking on an internet function that might seem unneeded or even ill—advised: helping teens talk to strangers.

Branded as “social discovery” services, these apps pitch themselves as alternatives to outlets that already specialize in online connections, like Facebook and Instagram. They say they are better at helping young users meet like —minded people outside their existing circles. And they say they have safeguards, such as separating users by age and using artificial intelligence, to protect against their appropriate or unsafe behavior that has plagued previous attempts to connect young people online.

Their user numbers suggest that, whether they succeed in striking the right balance, apps like Yubo and Hoop are tapping into a need among teens and 20 —somethings for new ways to branch out online.

“There is no place today to socialize online,” says Sacha Lazimi, the 26—year—old French co—founder of Yubo, which connects strangers with messaging and live streaming.

It is a counterintuitive statement for anyone who had seen teens sending Snaps rapid fire to their friends, responding to videos on TikToK, Face Timing for hours, or using Instagram. But Mr. Lazimi thinks those platforms allow for too much passive participation. “Snapchat, Instagram and Tik Tok are all about performance, content and individual”, he says.

Yubo features a swiping interface similar to that of Tinder. But Mr. Lazimi insists it is not adating app. The point, he says, is to facilitate communication between people all over the world who share mutual interests. Yubo isn’t present everywhere in the lives of American teens yet —and may be never will be—but the company says the app has 25 million users signed up, with nearly half of daily use now coming from America.

But some of these apps have also been the subject of safety concerns. Yubo has also faced its own safety challenges. In Florida, law—enforcement officially say they arrested a man who reportedly lured a teenager through Yubo.

In a statement, Yubo said that the prevention of child abuse has been a key priority for the past three years. “Yubo recognizes its responsibility in protecting young people using its service and has gone far beyond many of the main social media services.”

However, actually teens are doing more to protect themselves than many give them credit for, says Dr. Hinduja. “They are doing something to keep themselves safe or we would have strikingly more victimization than we do.”