【推荐1】Over seven months have passed since Panamanian officials launched an expansion of the world famous Panama Canal. Officials agreed to the expansion so that many of the world’s largest cargo ships (货船) could easily pass through the canal. Yet the $ 5.25-billion project has problems. It says ships still continue to rub against the canal’s walls and wear out its defenses designed to protect both shipping and the waterway.

A dangerous system

The canal links two oceans-the Atlantic and the Pacific-through a system of locks (船闸). The locks are like steps. They raise and lower ships from one part of the waterway to another on their trip from ocean to ocean.

With the old locks, which are still in use, large ships would be tied to powerful engines on both sides. These engines help to keep the ships in the center of the canal. In the new locks, the ships are tied to tugboats (拖船). One tugboat is tied to the front of the ship, with the other tied to the back. These boats then guide the ships through the canal.

At first, pilots of the cargo ships and tugboat operators would sometimes try to rub the boats against the canal walls as a way to keep the ships straight. But this caused damage to rubber padding (垫料) lining the walls.

Not enough training

Even before the expanded canal opened in June 2016, tugboat operators had expressed concern about the new system. Many asked for more training. The fears and dangers remain, although the boats are going through.

The Panama Canal Authority reports that, between June 2016 and January 2017, there were only 15 incidents that resulted in damage to locks or ships. That represents about 2 percent of the 700 times ships that have sailed through the expanded canal.

Pilots have argued they should be replaced with a system of floating bumpers (减震) like those used in some European locks. Officials say they plan to continue operating with the current system of defenses, but changes could happen in the future.

【推荐3】If you live in southwest Virginia, don’t be surprised at the sight of a drone(无人机) winging its way, doing airborne delivery over your neighborhood.

On October 20,2019,wing,an American multinational company, began the most advanced trials of commercial drone delivery in Virginia. Residents can now use a smartphone app to order items from Wing partners such as Sugar Magnolia. A Wing drone never sets down at destinations, instead gently lowering the package with a rope outside the customer's door.

Though Wing is the first American company to receive Federal Aviation Administration(FAA)approval to use commercial drones as a widespread service. it is not the only one. On October 22,2019,multinational delivery company UPS, which had also received FAA approval for its drone fleet, announced it would soon begin trial deliveries of goods from health care company CVS. Meanwhile, ridesharing company, Uber, which had partnered with McDonald's, hoped to use its drones to deliver food to hungry customers in San Diego, CA, before the end of 2019. Amazon also plans on testing its trial deliveries of goods in a yet-to-be-determined location in the upcoming months.

Every company's drones can carry packages weighing up to five pounds, and the series of trial are hortative, but widespread drone delivery still has many challenges. These include basic issues like finding places for drones to land, reducing noise pollution, and even ensuring the drones don't run into each other while airborne.

To help sped up the process, NASA announced the Urban Air Mobility Grand Challenge. The competition challenges airspace service providers to find creative solutions to the issues, so that drone deliveries can become a reality soon. “We are moving fast,” said NASA Administrator Jim Bridenstine. “We want to see by 2028 at least one city--maybe more than one--have the ability to control hundreds of drone delivery systems. They could be carrying goods, doing thousands of missions every day.”

【推荐3】People You’ve Never Heard of Who Changed the World

It is a fact that most people live their lives unremarked by history. Whether by design or by accident, there are some pioneers whose achievements changed the course of history but whose names are unknown to us.

James Harrison has saved the lives of over two million people by donating his blood 1,173 times, a Guinness world record. His blood produces a rare antibody (抗体) which cures the otherwise deadly Rhesus disease in unborn children. It has also been used in the development of a medicine anti-D, which will cure the Rhesus disease in children forever.

After helping Alexander Graham Bell obtain his patent for the telephone, Lewis Latimer patented a carbon filament (碳灯丝), which allowed light bulbs to burn for hours before burning out, much more useful than that invented by Thomas Edison. Latimer went on to invent many other useful devices, including a device which cooled and cleaned patients’ rooms in hospitals.

Not all achievements require bravery and self-sacrifice. Take Maurice Hilleman for example. He found another way to change the world. He developed the mumps vaccine (疫苗) after his daughter got the illness. And he didn’t stop there. In total, he has single-handedly developed over 40 vaccines, including eight commonly given to children. His work has saved millions of lives and prevented serious consequences due to the diseases.

In 1959 Nils Bohlin patented a revolutionary design that has saved millions of lives － the three-point safety belt. After the initial resistance from drivers who hated being told what to do, and even for their own good, the three-point belt has become a standard feature in new cars around the world.

【推荐2】It’s summer, and school-aged kids are finding all kinds of ways to have fun, from a trip to the pool or playground to playing games with smart phones. As a result, they are also forgetting some of what they learned in school, a phenomenon (现象) called “summer slide”. Fortunately, summer slide can be prevented with just a little regular practice of fun.

Encourage reading every day. Make a special event out of a trip to the public library, and let your kids pick out whatever interests them. Give your kids a special treat for every book they finish. Help them set up a reading corner in their room that’s quiet, comfortable and free of various electronic distractions. Best of all, give them the gift of your own example as an enthusiastic reader.

Another way to make reading fun is to share a poem together. Poems by writers like Dr. Seuss, Shel Silverstein and Maurice Sendak are fun to read aloud, and often have a strong sense of humor that attracts children. Take turns reading them aloud to each other, talk about what they mean, and see if you can memorize your favorites. Then have a contest to see who can write the best poem.

Summer is a great time to visit a learning place together. Children’s museums are specially designed to make learning fun and enjoyable for kids and let them practice essential skills. Or just take a walk together on one of our many nature paths, where your children can use their reading skills to learn about the plants, animals and geology around them. And of course, don’t forget the special programs offered by many local public libraries, along with many other learning materials for kids of all ages.

【推荐3】It is one of the greatest mysteries of nature. In case you haven’t noticed, all living things follow very definite, individual rhythms, all as regular as a clock, but what makes them regular?

Though many scientists maintain that these rhythms are the result of some outside force like gravity or radiation or both, the results of most scientific researches agree with other scientists who believe that each living thing has its own built-in biological “time clock.”

Take the mystery of migration for example. Scientists can’t really explain why many species of birds migrate in the autumn even though the temperature is still summery. The birds just seem to snub the comfortable weather that they are having. When a certain time comes, they travel south by the thousand. In spring time, they migrate northwards when though there probably is snow still covering the ground when they finally arrive. Something said “go”, and they did.

Animals that hibernate are obeying individual time clock, too. When their clock indicates the time to take a winter’s nap, they do, and nothing can stop them. At a certain time in the spring, they wake up and come out regardless of the weather outside.

Plants appear to have yearly rhythms, such as the sprouting(发芽)of seeds, and they also have daily rhythms. Notice sometimes that plants raise their leaves in daylight and lower them at night.

If you live along the California coast, you can easily observe a demonstration of this mysterious clock functioning regularly. There, from February to September, the highest tides occur exactly every fourteen and four-fifths days, and during these high tides, but at no other time, small silvery fish called grunions surf-ride a wave to the beach. There the female deposits her eggs in the sand and the male, fertilize them; then both hitch a wave-ride back to the sea. Exactly fourteen and four-fifths days later, never before or after, the tiny eggs hatch, and the high tide carries the new habits out to sea.