1 . The impressive collection of literature in the Library Cave at the Mogao Caves in Dunhuang, Northwest China’s Gansu province, ______ one of the most inclusive, advanced and open _______ of the ancient Chinese, says Dunhuang specialist Zhao Xiaoxing.

______ in the Hexi Corridor, the main line of the ancient Silk Road, the caves, a UNESCO World Heritage Site, have been promoting goods and cultural ______between the East and the West for more than 1,600 years.

While the Dunhuang wall paintings have recorded the glories of the past ______ , the more than 60,000 items of literature______ in the Library Cave, or Cave 17, dating from the 4th to the 11th centuries, have kept the ______ original quality through the written word, according to Dunhuang Academy.

The value of the ______ was thoroughly demonstrated during the launch of the Digital Library Cave, a gamelike program ______ enables users to virtually witness, and participate in, the_________ and fall of the Library Cave on the website Digital Dunhuang or via the WeChat miniprogram, Cloud Museum of Dunhuang Caves.

The Library Cave ______ in the mid-9th century and later______ unopened for almost 1,000 years ____ being accidentally discovered by Taoist priest Wang Yuanlu in 1900.The majority of its cultural relics, consisting of Buddhist manuscripts, ______ and economic documents and other delicate and ______items, are now kept in foreign museums.

2 . The Language of Flowers

Ding dong! I looked up from the couch. Who in the world could that be? My body was troubled with illness, so I’d ________myself away. Friends telephoned, texted, emailed and sent cards. I didn’t ________, thinking that I had nothing to offer anyone in the miserable condition I was in.

I ________got up and opened the door to a flower delivery. As I put the flowers on my dining table, I was struck by its ________. It was comprised of solitary blossoms of many varieties that shouldn’t really ________yet somehow did. The mystery flowers had come in a blue jar, without a card.

Instead of returning to the couch, I ________ the florist. He told me some of my friends were behind the ________, secretly. “They wanted to get a ________to you, ” he said, “through the language of flowers.”

The group had followed him and picked very ________stems after consulting an old book. “I learned some things,” the florist said, then ________: “The red carnation (康乃馨) meant ‘Our hearts ache for you’. The yellow tulip (郁金香) wanted to see ________in my smile again. The pink carnation had a few ________words to say about never forgetting me.”

The more I understood what the flowers were ________, the more I started to remember the woman who might have ________them before I separated myself from everyone and everything. My friends knew I was still that woman, with ________beyond my health.

3 . Bringing Mosquitoes Under Control

Every year, hundreds of thousands of people die of mosquito-borne diseases like malaria and dengue fever. Drug treatments are ________, and, despite decades of effort, vaccines have, for many of these diseases, proven to be difficult to develop.

It is better, then, to stop these infections happening in the first place by ________ doing away with the mosquitoes that carry the diseases. CRISPR-Cas9, a new and powerful genetic-engineering process, could help to do just that.

Craig Montell, of the University of California, and his colleagues have used CRISPR to ________ an existing control method called the sterile insect technique (SIT), which involves releasing lots of sterilized (绝育的) males into the wild. Females that mate with these males produce no young. ________ releases can reduce populations dramatically. SIT has been used in North America to eliminate screwworm flies, an agricultural pest.

SIT has been tried on mosquitoes, too, but with less ________. One reason seems to be the side-effects of the procedure. To sterilize them, males are exposed to poisonous chemicals. This works, but it damages them in other ways, too. The result can be sickly individuals that ________ to compete in the mating game with wild mosquitoes.

Montell and his colleagues hoped that CRISPR might offer a(n) ________. Their first step was to look for genes which affect fertility (可繁殖性) in mosquitoes. They began their hunt in fruit flies and ended up focusing on a gene that, when ________, made male fruit flies sterile. The gene was present in a similar form in their target mosquito species, Aedes aegypti, which passes on, among other illnesses, yellow fever, dengue and the Zika virus. Disabling the ________ gene in male Aedes likewise left them infertile. ________, the genetic changes involved did not appear to affect the engineered mosquitoes in any other way. On every measure of ________, they performed as well as wild mosquitoes.

________ the details are not fully understood, once female mosquitoes have mated a few times, they become unwilling to do so again. Mating with an infertile male is, therefore, not only fruitless in itself, but should also leave a female less interested in ________ males.

There is more work to be done before field trials, but having established the ________, Montell is excited to see where the work might lead. That the engineered males leave no young means that there are fewer worries surrounding any ________ consequences which might arise from the release of millions of genetically edited creatures into the environment. And that the target gene is found in both fruit flies and Aedes suggests it is likely to exist in other disease-carrying mosquitoes, too.