On the eve of our daughters' weddings, I gave both of them what Iconsidered to be excellent marital advice: never leave your husband unsupervised(无人监督的) with pruning shears (修枝剪).

If only I had taken my own advice. I recently let my guard down. Thirty-some years of marriage can do that toa woman. Give a man pruning shears and electric trimmers (电动修剪器) and he will givenew meaning to “armed and dangerous.”

One day earlier this year, my husband saidthat the crab apple tree was dead.

“Why do you think it is dead?” I asked.

“Look at it. There's not a leaf on it.”

“There's not a leaf on anything. It'sMarch,” I said.

“It looked sick last fall and with thisbitter winter we had, I'm convinced it's dead.”

The truth is he's never liked thecrabapple. Sure, it has beautiful blooms in the spring, but then it gets adisease, the leaves curl, and it drops those little apples that sit on thedriveway.

Each passing week he pronounced the treedead. Eventually I began to believe him. Though he agreed it would be aregrettable loss, there was a twinkle in his eye. He armed himself a couple ofweeks ago and began trimming. A branch here, a branch there, a small limb, thena large limb. I watched and then decided to check the wood on some of thebranches closer to the trunk. I broke one off and saw green.

The crabapple was not dead. It just hadn'thad time to leaf out. The tree was now falling to one side, but it was notdead. I would have told him so, but he had moved on to a maple. Once the manstarts, he can't stop. One trim leads to another.

“Please, stop!” I called.

He smiled and nodded, but he couldn't hearbecause he had started the hedge (树篱) trimmers and was getting ready to fix a line of hedges.

Zip (飕飕声), zip, zip.

“What do you think?” he shouted.

“It's supposed to be a privacy hedge; nowall that will be private are our ankles.”

He started the trimmers again.

“Stop!” I called, “Come back!”

“Why?” he shouted.

“You're in the neighbor's yard.”

A Pacific Science Center Guide

◆Visit Pacific Science Center's Store

    Don't forget to stop by Pacific Science Center's Store while you are here to pick up a wonderful science activity or souvenir to remember your visit. The store is located(位于) upstairs in Building 3 right next to the Laster Dome.

◆Hungry

    Our exhibits will feed your mind， but what about your body? Our café offers a complete menu of lunch and snack options, in addition to seasonal specials. The café is located upstairs in Building 1 and is open daily until one hour Pacific Science Center closes.

◆Rental Information

    Lockers are available to store any belongings during your visit. The lockers are located in Building 1 near the Information Desk and in Building 3. Pushchairs and wheelchairs are available to rent at the Information Desk and Denny Way entrance. ID required.

◆Support Pacific Science Center

    Since 1962 Pacific Science Center has been inspiring a passion(热情) for discovery and lifelong @ in science, math and technology. Today Pacific Science Center serves more than 1.3 million people a year and brings inquiry-based science education to classrooms and community events all over Washington State. It's an amazing accomplishment and one we connect achieve without generous support from individuals, corporations, and other social organizations. Visit pacificsciencecenter.org to find various ways you can support Pacific Science Center.

    The following children's books are our top picks to read together every year on Christmas Eve.

    Snowden written by Nancy Carlson

    This book is aimed at pre-school to the third-grade children, but can be enjoyed by many older children as well. Snowden is the story of a little girl and the snowman she makes that magically comes to life. Together, the two learn to ice-skate and discover that “a little magic and a lot of practice” can make all the difference in the world. The story is heart-touching and sweet.

    The Polar Express written by Chris Van Allsburg

    A young boy cannot sleep on Christmas Eve and is swept away by a steam engine on a trip to the North Pole. During the adventure, the message is that believing will keep you young at heart. The bell that the boy receives and his belief are both touching. The illustrations leave enough to the imagination to make it easy to fall into the story yourself.

    A Snowman Named Just Bob Written by Mark Kimball Moulton

    This book shares a tale of lasting friendship and teaches the lesson that friendship is always in your heart. The illustrations are beautiful and the text is eye-catching. The lessons are taught in such a way that they do not overshadow (使失色) the actual story. I tear up every time I read this book to my children.

    Starting Cycling

    We have two services designed to give people the confidence and knowledge to cycle successfully.

    Lessons

    All our instructors have been trained to National Standards level of “Bikeability”. This means you will be trained to a standard consistent across the whole country.

    There are 3 levels of skills to progress through. Children would start with levels 1 & 2, progressing from the playground or park to cycle on less busy local roads. Teenager and adult beginners can also learn levels 1 & 2 in an off-road and quiet environment.

    Confident teenagers and adults can broaden their skills by learning level 3, using multi-lane (多道) roads and larger roundabouts (环岛). We provide both a complete package of lessons for the beginner or individual lessons tailored to the client. You can ride a bike but don't feel confident about right turns on multi-lane roads. Whatever the need we can address and practice until perfect!

    Everyone can be taught to ride a bike!

    We train both adults and children.

    We cover London Zones 1 & 2

    The cost is ￡30 per hour.

    Guided Ride

    We know that riding on the roads in London can be scary, and if you have to navigate (确定行车路线) as well it can become a real hard task! The Guided Ride service takes all the stress out of it for you by providing the following:

    Route planned in advance to suit your skill level. Route map provided to you.

    Cycle and equipment checked. We will teach you a simple method to check basic roadworthiness (车辆性能) of your bike that you can perform on a weekly basis.

    Route discussed and focus given to any areas requiring special attention.

    Cycle along with the instructor close behind. Here the traffic can be controlled by the instructor and rider observed.

    Occasionally stopping to discuss events.

    We currently cover London Zones 1 & 2. Please contact us if your requirements are outside of these areas.

    Cost ￡30

    If you could have a superpower, what would it be? Other than flying and communicating with someone from his mind (which, let's be honest, would probably actually be awful), breathing underwater is one of the favorites. You can hang out with Aquaman and Ursula, and when the end of the world comes and we're all living under water, you'll be fine.

    With this in mind, a student at the Royal College of Art, London has designed a 3D-printed amphibious garment called AMPHIBIO —essentially a set of gills (鳃) —for this very purpose. According to Jun Kamei, a biomimicry designer and materials scientist, it is "for a future where humankind lives in the water".

    With the world set for a global temperature increase of 3. 2℃ (5. 7℉) by 2100, rising sea levels are a very real threat to large coastal cities, potentially affecting up to 2 billion people —or 26 percent of the current global population.

    Kamei's little device uses a specially designed porous (多孔的) material that fills oxygen again in the water and releases carbon dioxide. It is inspired by water-diving insects that create their own little scuba diving set by creating a protective bubble of air around their body thanks to their water repellent (防水的) skin.

    The technology is easily 3D-printable too, which will be great when we need them together. These "gills" could replace heavy and clumsy scuba equipment, making it more similar to free diving but for longer. This could have immediate applications for underwater rescue plans —the 12 boys rescued by divers from a flooded cave in Thailand, for example, where it took weeks to work out how to get the boys and the vital breathing equipment through those narrow tunnels.

    So far, the tech has only been tested as a working prototype, not actually on humans, so the dream may have to be on hold for now. And scaling up and testing on humans is Kamei's next plan. This may sound unbelievable, but Kamei insists he has a much more optimistic vision of the future.

    Dujiangyan is the oldest man­made water system in the world, and a wonder in the development of Chinese science. Built over 2, 200 years ago in what is now Sichuan Province in Southwest China, this amazing engineering achievement is still used today to irrigate over 6, 000 square kilometers of farmland, take away floodwater and provide water for 50 cities in the province.

    In ancient times, the region in which Dujiangyan now stands suffered from regular floods caused by overflow from the Minjiang River. To help the victims of the flooding, Li Bing, the region's governor, together with his son, decided to find a solution. They studied the problem and discovered that the river most often overflowed when winter snow at the top of the nearby Mount Yulei began to melt as the weather warmed.

    The simplest fix was to build a dam, but this would have ruined the Minjiang River. So instead Li designed a series of channels built at different levels along Mount Yulei that would take away the floodwater while leaving the river flowing naturally. Better still, the extra water could be directed to the dry Chengdu Plain, making it suitable for farming.

    Cutting the channels through the hard rock of Mount Yulei was a remarkable accomplishment as it was done long before the invention of gunpowder and explosives. Li Bing found another solution. He used a combination of fire and water to heat and cool the rocks until they cracked and could be removed. After eight years of work, the 20­metre­wide canals had been carved through the mountain.

    Once the system was finished, no more floods occurred and the people were able to live peacefully and affluently. Today, Dujiangyan is admired by scientists from around the world because of one feature. Unlike modern dams where the water is blocked with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally, enabling ecosystems and fish populations to exist in harmony.