一. 马航事件(创新科技类话题)

We can see countless millions of miles into the blackness of space, but a 3-mile depth in the ocean is testing the very limits of our technology because most of it just doesn’t work underwater.

As the hunt for Malaysia Airlines Flight 370 demonstrates, at that depth — minuscule compared with the vastness of space — everything is a virtual unknown. A high-tech unmanned underwater submarine, Bluefin-21, has been dispatched four times to look for wreckage from the jet, but the crushing water pressure and impenetrability of this void mean that only its most recent pair of missions were completed. Scrutinizing dust and rock particles on the Red Planet, tens of millions of miles away, is a breeze. Understanding what’s on the seafloor of our own planet is not.

About 95% of deep ocean floor remains unmapped, but that’s almost certainly where the most sought after aircraft in history is going to be found. “Our knowledge of the detailed ocean floor is very, very sparse,” Erik van Sebille, an oceanographer at the University of New South Wales in Sydney, tells TIME.

The reason for our ignorance is simple. Virtually all modern communications technology — be it light, radio, X-rays, wi-fi — is a form of electromagnetic radiation, which seawater just loves to suck up. “The only thing that does travel [underwater] is sound,” says van Sebille, “and that’s why we have to use sonar.”

Sound is formed by mechanical waves and so can penetrate denser mediums like liquids: but at a 3-mile (5 km) depth, even sonar starts to have problems establishing basic parameters. The waters in which the search for MH 370 is happening, for example, were thought to be between 13,800 and 14,400 ft. (4,200 and 4,400 m) deep, because that’s what it said on the charts that had been drawn up over time by passing ships with sonar capabilities. It turns out those seas are at least 14,800 ft. (4,500 m) deep. We only know that now because that’s the depth at which Bluefin-21 will automatically resurface — as it did on its maiden foray — when onboard sensors tell it that it’s way, way out of its operating depth. The problems with Bluefin-21, van Sebille says, show us that “even our best maps are really not good here.”

The other issue affecting visibility is the sheer volume of junk in the ocean. About 5.25 trillion particles of plastic trash presently billow around the planet, say experts, weighing half a million tons. There are five huge garbage patches in the world’s seas, where the swirling of currents makes the mostly plastic debris accumulate. The largest of these is the Great Pacific Garbage Patch, a gyre measuring an estimated 270,000 to 5.8 million sq. mi. (700,000 to 15 million sq km). This refuse gets ingested by plankton, fish, birds and larger marine mammals, imperiling our entire ecosystem.

Flotsam debris has already impeded the hunt for MH 370. Hundreds of suspicious items spotted by satellite have sent aircraft and ships on hugely costly detours to investigate what turned out to be trash. (On Friday an air-and-surface search continued, with 12 aircraft and 11 ships scouring an area of some 20,000 sq. mi. [52,000 sq km] about 1,200 miles [2,000 km] northwest of Perth.) Officials are saying that such efforts are becoming futile.

For all we know, Bluefin-21 could also be confused by the sheer volume of garbage down there. According to a study by the Monterey Bay Aquarium Research Institute published last June, based on 8,000 hours of underwater video, an unbelievable quantity of waste is strewn across the ocean floor. A third of the debris is thought to be plastic — bags, bottles, pellets, crates — but there is a vast amount of metal trash as well, including many of the 10,000 shipping containers estimated to be lost each year.

“I was surprised that we saw so much trash in deeper water,” said Kyra Schlining, lead author on the study. “We don’t usually think of our daily activities as affecting life two miles deep in the ocean.

That’s because we can’t see it. It’s tempting to say that MH 370 might as well have vanished into space — only if it had, we’d have found it by now.

二. 奥巴马新移民政策 (政权类话题)

President Obama has long insisted he does not have the power to waive deportations of illegal immigrants on his own.

But under pressure from political allies, Mr. Obama may be headed for some changes of immigration policy via the Department of Homeland Security. DHS Secretary Jeh Johnson is considering limiting deportations of undocumented immigrants who do not have serious criminal records, the Associated Press reported Monday.

Obama set the stage for the reported recommendations last month, when he ordered Secretary Johnson to review how current immigration law is implemented, with an eye toward conducting enforcement “more humanely,” as the White House put it.

The change of policy, if adopted, “could shield tens of thousands of immigrants now removed each year solely because they committed repeat immigration violations, such as reentering the country illegally after having been deported, failing to comply with a deportation order, or missing an immigration court date,” the AP reported.

Such a move would fall short of the larger changes pro-immigrant activists are hoping for, such as granting work permits to the illegal-immigrant parents of American-born children. At the same time, any unilateral move by the administration that grants new rights to certain illegal immigrants would likely anger Republicans, who accuse Obama of abusing his executive powers.

The president has long said the only way to achieve comprehensive immigration reform is to go through Congress. But almost a year after the Senate passed reform legislation on a bipartisan vote, the Republican-controlled House has yet to act.

Emily Cox (适用思想品德，成功与失败等话题)

Perhaps after hearing this young lady's story, Harvard will move her from the wait list to accepted status.

As the 118th Boston Marathon begins Monday, Fairfax (Va.) W.T. Woodson High senior Emily Cox is the youngest female competitor in the field of 36,000, according to a fantastic Washington Post feature.

Marathons run in Cox's blood. Her grandfather John Jr., a World War II veteran, got the family running. Literally. They've reportedly competed in 101 Marine Corps Marathons since 1986. According to The Washington Post, Emily ran her first marathon to honor her grandfather's death in August 2011 — finishing in 4:35.08 despite never training — and this year's 26.2 miles will have similar significance.

"I'll have something to run for this year, more than me just trying to finish a marathon,” she told the paper. "Ultimately I know I’ve trained well. I have to trust my training and have fun. I want to have a smart pace, go out and just enjoy it, enjoy the experience, enjoy Boston and be part of something bigger than myself."

Cox qualified for the first Boston Marathon since the bombings in 2013 with a time of 3:31.51 at last year's Marine Corps Marathon, according to The Washington Post. She turned the minimum age of 18 on March 30, making her the youngest female to take to the starting line in Hopkinton, Mass.

All of this despite running just one season for Woodson. Her endurance comes from years of tennis completion before dropping the sport to focus on academics as a high school freshman, the paper said. Instead, she has reportedly run nine miles a day since her sophomore year, waking up daily at 3:45 a.m.

Meanwhile, many of her peers would be sleeping seven hours later if they had their druthers. It seems there's a reason she's been accepted to Brown University, the University of Virginia and the College of William and Mary. Harvard and Columbia reportedly wait-listed her. Considering she's running in the Crimson's backyard on Monday, perhaps they'll finally recognize this trailblazing teen.

教师简介：

姚骏鹏，上海新航道新托福、雅思、SAT、GMAT主讲，澳大利亚昆士兰大学英语翻译与口译硕士，悉尼大学人力资源管理硕士。7年英语写作及演讲经验，中英三级笔译/二级口译(获澳大利亚翻译口译资格认证委员会认证)。2004年悉尼大学中国留学生联谊会“堪培拉奥运圣火”悉尼Burwood地区负责人。丰富的海外经历结合扎实的英语功底，课堂思路开阔，授课效率高。