My dad is a busy engineer. Every Saturday he puts on his apron and makes very delicious bread. I think he bakes to _______.

These days I feel stressed out because I failed in the test of our school swimming team. That means I have to wait for a whole year to try out again. Maybe my dad knew how I _______, so this Saturday he invited me to help him bake.

He took out all the things needed and told me to _______ the ingredients (配料) with a spoon. Then he showed me how to knead the dough (揉面团). It took only ten minutes but a(n) _______ large amount of energy to complete. Next came the _______ part—doing nothing. We waited for the dough to become _______, then pouched (锤打) it down and wait for it to rise again. Dad said _______ is always the hardest part as you have to refuse the thought of putting the dough directly into the oven.

While we waited, we sat and talked._______ is like the dough that rises and fills a room with emptiness unless you pouch it down with words. It felt good to listen and share our thoughts. A dough always rises at its own pace and we could do nothing to make it _______ faster.

I learned how to bake, and I also learned to ________ the slowly ticking rhythm of time, to relax and let the bread rise.

A group of scientists from China and other countries are working together to help learn more knowledge and appreciation of China’s ancient cultural heritage (遗产). They are recording and collecting digital images of cultural relics (遗迹) from the Mogao Caves, which were a key stop along the Silk Road throughout China’s ancient history. Nearly 500,000 wonderful digital photographs have been produced since the international project started in 1994.

The Mogao Caves have long been a meeting point for different cultures and are part of the history of many countries. Today, the caves are just as international as they were at the time when people travelled the Silk Road. Tourists from all over the world visit Dunhuang to see the caves, and the Getty Museum in Los Angeles has even reproduced a copy of the caves and paintings for people to appreciate in America.

By sharing so many digital photos over the Internet, the group hopes to help develop even wider interest around the world in China’s ancient history, culture, and traditions. They also hope to further educate people about the importance of safeguarding historic and cultural relics for future generations to understand and appreciate. As one scientist who is working on the project explains, “Appreciating one’s own cultural heritage is very important for understanding oneself. Appreciating the cultural heritage of other countries is very important for international communication and understanding.”

A pair of tusks (长牙) is usually an advantage for elephants, allowing them to dig for water, peel bark (剥树皮) for food and protect themselves. But because of illegally hunting, those big tusks may invite danger. Now researchers are working out how years of civil war and hunting in Mozambique have led to a greater number of elephants that will never develop tusks.

During the war from 1977 to 1992, fighters on both sides killed elephants for ivory to provide fund for the war. In the Gorongosa National Park, around 90% of the elephants were killed. The survivors shared a key feature: half the females were naturally tuskless — they simply never developed tusks — while before the war, less than a fifth lacked tusks. More confusing, two-thirds of the new-born elephants were female.

Like eye color in humans, genes (基因) are responsible for this. They found that the mothers have produced the smoking-gun genes for genetic changes. They pass the changed gene to both sons and daughters, but the sons are likely to die early in development. Daughters stay by their mother, many growing tuskless.

Most people think of development as something that goes on slowly, but humans can speed it up. “When we think about natural selection, we think about it happening over hundreds, or thousands of years,” said Samuel Wasser, a scientist at the University of Washington. “The fact that tusklessness happened over 15 years is one of the most surprising findings.”

Now the scientists are studying what more tuskless elephants mean for the species (物种) and its environment. “The changes will last for at least quite a few elephant generations. If an elephant doesn’t have the tool to peel bark from trees, then what chain reactions will happen?”