3 . You can pay a fortune to travel around the world. Or you can pay nothing at all. Here are some places you'll never regret visiting. They won't cost you a dime.

The British Museum, London(U.K.)

You need to go here to see the Egyptian mummies, the ancient Greek Marbles and so many other treasures. It's open every day, and unlike most other attractions in England that cost much money, it's completely free.

National Mall, Washington D.C.(U.S.A.)

You can walk a pathway from the Lincoln Memorial to the severe Vietnam Veterans Memorial and to the Washington Monument with other sights in between. Do you know you can go up in the elevator to the top of the Washington Monument? Tickets are free, but pay a small fee to reserve them in advance to avoid being disappointed.

Notre-Dame Cathedral, Paris(France) .

This great treasure of the world simply can't be missed. The great stained-glass rose window alone is worth the visit. The Sunday Mass with the Gregorian chant was like stepping back in time. Admission is free every day, but you're welcome to leave a donation. There are also free tours a few times each week. You'll pay extra for tours of the bell tower or the crypt.

National Museum of Ireland , Dublin and Mayo (Ireland)

Want to see bog bodies, gold ornaments, Viking artifacts and learn about rural Irish life? All four branches of this museum are free to visit, including museums devoted to archaeology, natural history, decorative arts and history and country life. The museum of country life in Tur lough Park, Mayo, is devoted to Irish rural traditions, while the natural history museum is especially famous for its collection of insects.

4 . Scientists say baby sharks are at risk of being born smaller and without the energy they need to survive because of warming oceans from climate change.

Scientists working with the New England Aquarium in Boston, Massachusetts studied epaulette sharks. They found that warmer conditions sped up the sharks’ growing process. That meant the sharks were born earlier and very tired.

John Mandelman is vice president and chief scientist of the Anderson Cabot Center for Ocean Life at the New England Aquarium. He said it is widely believed that epaulette sharks are “hardy,” or able to survive difficult conditions. “What it means is this very resilient species is more vulnerable than we thought, and this could be true of other sharks,” he added.

The scientists studied 27 sharks using the New England Aquarium’s reproduction program. Some were raised in average summer water temperatures, about 27 degrees Celsius. Others were raised in higher temperatures around 29 degrees Celsius and 31 degrees Celsius. They found that the sharks raised in the warmest temperatures weighed much less than those raised in average temperatures. They also showed reduced energy levels.

Epaulette sharks can grow to a length of about one meter. Their name comes from large spots on their bodies that look like decorations on some military clothing. The sharks are listed as stable and a species of “least concern” on the International Union for Conservation of Nature Red List of Threatened Species.

One study this year found that worldwide numbers of oceanic sharks and rays dropped more than 70 percent between 1970 and 2018. Overfishing is a main concern, while climate change and pollution also threaten sharks. Mariah Pfleger is an ocean scientist at the protection group Oceana. She said the study should serve as a warning to ocean governing agencies that careful supervision is needed to prevent the loss of more sharks. “This study further exemplifies that sharks will not be immune to a warming ocean,” Pfleger added.

6 . My 12-year-old daughter, Lauren, came home from school yesterday, proudly waving her grade book to me. She had been awarded A-1 in most subjects such as mathematics, language arts and science—a great achievement! Then she sadly pointed out that her perfect score was damaged by a B-1 in French and a C-1 in Physical Education.

I asked her what the scores meant. She said that the letter showed the achievement(成绩) and the number showed the effort. That moment I realized that the grades were misleading. I reached out my hands and gave her a big hug and told her in my mind she had a perfect score. It didn’t matter that her grade in French was a “B”—the “l” showed that she had tried her best. That is something to make any parent proud.

Everybody is different. Everybody has different potential(潜能). Not all of us will become linguists(语言学家) or sports stars. But without 100％effort no potential can be achieved. If I see a salesperson fail at sales, the first thing I want to examine is the effort being put in. If there is a problem with effort, the salesperson has no future. But if I see a salesperson isn’t successful with l00％effort, he or she is worth my effort in helping. Maybe a bit of training or some advice from a more successful person will help. I know that 100％effort, focus in the right direction, will always bring a result whether that is an “A” or a “C”. As long as you make 100％effort, you are great.

8 . Plants: we eat them, juice them-and now it seems we can mine them too!

After a successful experiment on the island of Borneo, the botany professor Alan Baker and a group of researchers want to introduce phytomining (harvesting minerals from plants) as a better, partial substitute for traditional mining.

Phytomining, also known as agromining, means collecting metals from live plants. However, this can only be done with a group of plants known as "hyperaccumulators". There are around 700 identified types worldwide, and what makes these hyperaccumulators special is that they naturally attract and absorb minerals through their roots-metals poisonous to other plants-and then store huge, pure concentrations of these minerals in their bodies. The metals can then be extracted from the plants' sap(汁;液), oil, or sometimes even live tissue.

Baker and his colleagues see a lot of potential in phytomining. Not only can it help meet the growing global demand for metals, but is a way of undoing some of that damage to the environment by traditional mining.

One of the biggest problems with traditional mining is that it pollutes the surrounding area. Phytomining can extract metal waste, plus planting the hyperaccumulators would regrow the deforested areas caused by mining operations. Aside from this, if phytomining is able to replace part of traditional mining, then there would be fewer instances of bad mining practices like abandoned mines, which pollute the nearby waters. Also, since phytomining provides metals that are already naturally pure, there is no need to use huge amounts of energy to purify the ore(矿石).

Phytomining has its drawbacks. Harvesting plants on a large scale is expensive today, compared to traditional mining. Besides, plants can be wiped out by diseases or unexpected weather conditions.

However, there are many reasons to consider phytomining. After all, we need to make sure that our planet can keep up and sustainable practices like phytomining give us the hope that our advancement doesn't mean sacrificing Mother Earth.

9 . Turtles have an unfortunate habit of eating plastic objects floating in the sea. These then cannot be broken down and digested, and may ultimately kill them.

It is widely assumed that this special liking for plastics is a matter of mistaken identity. Floating plastic bags, for instance, look similar to jellyfish, which many types of turtles love to eat. Yet lota of plastic objects that end up inside turtles are not similar to jellyfish. Joseph Pfaller of the University of Florida therefore suspects that the smell of micro-organisms (微生物) which grow on floating plastic objects fools turtles to feed.

Researchers at the University of California noticed that certain chemicals, which are released into the air by micro-organism — colonised plastics, are those which many seabirds sniff to track down food. These chemicals mark good places to hunt because they indicate an abundance of the seaweed and bacteria. Since turtles are known to break the surface and sniff the air when swimming towards their feeding areas, Dr. Pfaller indicated that they are following these same chemicals, and are fooled into thinking that floating plastic objects are edible.

To test that idea, he and his colleagues set up an experiment. They arranged for 15 of the animals, each around five months old, to be exposed, in random order, to four smells delivered through a pipe to; the air above an experimental area. The smells were: the vapour from deionised (去离子) water; the smell of turtle-feeding meal; the smell of a clean plastic bottle; and the smell of a similarly plastic bottle that had been kept in the ocean for five weeks to allow seaweed and bacteria to grow on it. Two of the smells-the smell of meal and that of five-week-old bottles-proved far more attractive to the animals than the others.

On the face of it, then, the turtles were responding to the smell of old bottles as if it were the smell of food. In an unpolluted ocean, pretty well anything which had this smell would be edible-or, at least, harmless. Unfortunately, five-week-old plastic bottles and their like are not.

10 . An unusual experiment in Botswana suggests that painting eyes on the rear (臀部) ends of cows may help protect them from large predators (食肉动物) like lions. Protecting cows could also end up protecting the lions from angry farmers.

Large predators like lions are under pressure. Much of the land they used to roam (徜徉) has been taken over by humans. Many are hunted illegally. One serious threat to large predators comes from farmers, who often shoot or poison them after losing farm animals for their attacks.

This has long been a problem in the Okavango Delta. Some parts of the Okavango are protected, but there are also many small farms in the area, with between 6 and 100 cows. Lions are the biggest threat to cattle in the area. At night, farmers normally keep their animals in closed areas protected from predators. But in the daytime, when many predators are most active, the cattle are allowed out to eat grass.

Scientists from the University of New South Wales wondered if painting pictures of eyes on the cows' rear ends might protect them. The idea isn't as strange as it may sound. There are many examples of animals such as butterflies or fish using fake “eyes” to protect themselves.

Working with over 2,000 cows 8 on 14 different farms in the Okavango area, the scientists tested their ideas in a four-year study. The researchers separated the cows into three different groups. They painted large eyes on the rear ends of one group of cows. The second group got simple Xs. The final group got nothing.

The eyes worked very well. Of the 683 cows with eyes painted on them, none were killed in the four-year period. Cows with nothing on their rear ends didn't do so well. Fifteen of the 835 cows with bare backsides were killed. The scientists were surprised to learn that even Xs seemed to give the cows some protection. Only 4 of the 543 cows with Xs were killed.