1 . In Dad’s Army, a British sitcom (情景喜剧) about a home-defense Force, Sergeant (中士) Wilson would often cast doubt on his commander’s various orders with the phrase “Do you think that’s wise, sir?” His doubt, although often ignored, was usually ________.

Many employees must be tempted to imitate Sgt. Wilson when they see their bosses head down the wrong track. But caution often leads workers to keep silent for fear of appearing foolish and offensive and ________ being at high risk of losing their jobs.

A culture of silence can be dangerous, argues a new book The Fearless Organization, by Amy Edmondson, a professor at Harvard Business School. Some of her cases are from the ________ industry, where staff felt too powerless to make any changes due to their ranks. One was its deadliest accident: a crash between two Boeing-747s in the Canary Islands occurred in 1977 when a co-pilot felt unable to ________ his captain into changing the decision to take off. Another case was that of the Columbia space shuttle in 2003; an engineer who may have diagnosed damage to the shuttle’s wing before the flight felt unable to speak as he was “too ________” at NASA.

In a corporate culture based on ________ and obedience, it may appear that targets are being achieved. But in the long run the effect is likely to be counterproductive (适得其反的). Studies show that fear ________ learning. And when faced with a problem, scared workers find ways of ________ it or getting around it with inefficient practices.

The solution is to create an atmosphere of “psychological safety” whereby workers can speak their minds. It does not mean that workers, or their ideas, are ________ criticism, or that they should complain continuously. In a sense, this method is the ________ of Toyota’s “lean manufacturing” process, which allows any worker who spots a problem to stop the production line.

Pixar, the production firm, created what it called a “Braintrust” to give ________ to film directors. The rules were that advice should be constructive and about the idea, not the person, and that filmmakers should not be ________ in response.

And psychological safety is not about whistleblowing (检举). Indeed, if an employee feels the need to act as a whistleblower by speaking to external ________, it suggests employers have not created an environment within the firm where criticism can be ________. Nor is such a culture only about safety or avoiding mistakes. As mundane (单调的) tasks are automated, and workers rely on computers for data analysis, the added value of humans will stem from their ________. But as Ms. Edmondson’s book demonstrates, it is hard to be either constructive or creative if you are not confident about speaking out.

Biographers (传记作家) gather information from many different sources. Legal documents and personal papers can reveal facts such as a person’s birthplace, income, number of children, and lifespan. Letters or a diary may contain valuable information about the person’s friends and activities, thoughts and feelings. All of these materials are called primary sources because they contain firsthand information ---- information that does not depend on the opinions or interpretations of others.

A biographer also checks secondary sources. The subject’s friends and relatives may be interviewed. If the subject died long ago, the biographer looks for anything written about him or her. Secondary sources supply secondhand information, and so a biographer must use them with care. The subject’s friends will want the biography to be favorable, while others may wish it to be unfavorable. The biographer must avoid both extremes. The biographer’s job is not to make readers like or dislike the subject, but to give as complete and truthful a picture of the person as possible. This means the biography should include both good and bad qualities, both accomplishments and mistakes. James Boswell, the author of a great biography of his friend Samuel Johnson, wrote, “And he will be seen as he really was; for I profess to write, not his panegyric (颂文), which must all praise, but his life, which, great and good as he was, must not be supposed to be entirely perfect.”

Much biographical writing falls short of Boswell’s standards. Ancient records of the deeds of kings and emperors were written to praise and flatter these rulers. Writers of saints’ (圣人) lives in the Middle Ages were often more interested in the moral message than the events of a life. Many 19th-century biographers did not reveal any improper or embarrassing details of their subjects’ lives. Though they may be interesting or inspiring, these works fail as biographies chiefly because their purpose is to point up a moral rather than describe an individual.

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A good grilling

As they reopen after lockdown, many restaurants are firing up their barbecues. Diners appreciate food grilled over glowing charcoal embers, but the     1     residents often do not. Pollution levels near restaurants can be     2     higher than average, because of emissions from kitchens. With the increasing popularity of indoor barbecuing, it is a problem that is set to get worse.

The researchers tested a commercial grill,     3     with the sort of multistage filtering system used in many — though by no means all — restaurants. Apart from typical pollutants and particulate matter, they also discovered polycyclic aromatic hydrocarbons (多环芳烃). These cancer-causing chemicals are mainly produced by the incomplete combustion (燃烧) of     4     and oil-based sauces. The researchers estimated that if their half-a-square-metre grill was used for nine hours a day, it would release between 400 and 500 kilograms of fine and ultrafine particulate matter into the air every year. With many restaurants using 2.5-square-metre grills 16 hours a day, the level of pollution from most commercial    5     would be much higher.

The researchers are investigating which extraction systems best protect all the people     6     such as the restaurant employees. Taller chimneys are one option. But Dr Aleysa, an expert in combustion technology, suspects they would just     7     the pollution elsewhere. The results of these tests will be published next year.

Meanwhile, Dr Aleysa’s team have come up with their own solution: a new kind of grill, which they reckon can cut pollutants by 90%. Dr Aleysa is reluctant to go into     8    . But the basic idea is that before being released to the outside, the fumes are sucked back down through the embers and into a combustion zone, where hydrocarbons and odour compounds are fully burnt. That lessens the need for expensive extraction systems and fiddly filters that must be     9     cleaned.

An industrial partner is keen to put the grill into production. It could go on sale by the middle of next year. It will cost a bit more than a standard grill, says Dr Aleysa. But he believes that would be offset by lower     10     costs. Better air quality around restaurants would be welcome. But the big test will be whether chefs believe the new grill can produce that same barbecue flavour.

American researchers say they have invented a method that could use salty water on Mars to produce oxygen and fuel,     1     would both be important elements to support future human exploration activities on the Red Planet.

Engineers at Washington University in St. Louis, Missouri, developed the new method. They created a machine called an electrolyzer. It can separate salty water into oxygen and hydrogen gases.

The team described the process in a study recently published in Proceedings of the National Academy of Sciences (PNAS). Scientists have already collected solid evidence     2     the planet likely holds a large supply today. But Mars is extremely cold. So, most of the water     3     (think) to exist in the form of ice.

The research team notes that any water that is not frozen is almost surely full of salt from the Martian soil. The usual methods for breaking water down into oxygen require the salt     4     (remove) first. This process can be complex, costly and harmful to the environment. The new method they invented can take salty water directly and convert it into oxygen and hydrogen.

The team carried out experiments with high levels of magnesium salts, which scientists believe likely     5     (exist) on Mars. The researchers also carried out the tests     6     temperatures similar to the Red Planet’s atmosphere.

The U.S. space agency NASA has also experimented with technology to produce oxygen on Mars. One device designed to do this will be tested as part of NASA’s Perseverance mission. Perseverance is a new explorer vehicle, or rover, that is currently on     7     way to Mars.

The engineering team said its method could even find valuable uses on Earth. “    8     (demonstrate) these electrolyzers under demanding Martian conditions, we intend to also use them under     9     (mild) conditions on Earth,” said Pralay Gayen, who is a postdoctoral researcher at Washington University and a lead writer of the study. “    10     such use could be in defense industries,” he added, “the method could create oxygen on demand for submarines. It may also be able to provide oxygen for researchers exploring new environments in the deep sea.”

Few countries have such a diverse and appealing“ Outdoors” as the USA. The landscape is     1     varied and spectacular. In the west there are Rocky Mountains with their     2     peaks, and in the east the forest-covered Appalachians, whose highest

summit is nearly 7000 feet. There is also an abundance of waterfalls, rivers, lakes that are small and intimate or     3     like the Great Lakes. In winter and spring, tourists are     4     by the clear skies and breathtaking multi-colored rocks of Arizona,Colorado and New Mexico.

Everything worth seeing in the USA is     5     to picnickers and vacationers by highways and unpaved secondary roads, which     6     people to places from where where they can push off onto the wilderness. Once in the wilderness,the chief worry will be, not how to avoid other hikers, but how not to get lost!

Many Americans, young and old, prefer camping in vehicles called"campers”. There exist many different kinds from the extremely extravagant to the cheap convertible pick-up truck. There are monster campers with every imaginable     7    , from deep freezers and microwave ovens, to plush carpets and color television sets.They can     8     four people comfortably.

Horseback riding also holds a     9     for many but it's a more expensive sport.There are ranches in Texas and other border states where you can stay and live the life of a cowboy or cowgirl. Other great outdoor pastimes for     10     can be skiing in the Rockies and hunting in Alaska, surfing, waterskiing in Florida.