Questions 26 to 35 are based on the following passage. The method for beer has changed over time. Hops (啤酒花)，for example, which give many a modem beer its bitter flavor, are a (26)_______ recent addition to the beverage. This was first mentioned in reference to brewing in the ninth century. Now, researchers have found a (27)_______ingredient in residue (残留物）from 5,000-year-old beer brewing equipment. While digging two pits at a site in the central plains of China, scientists discovered fragments from pots and vessels. The different shapes of the containers (28)_______ they were used to brew, filter, and store beer. They may be ancient “beer- tools,” and the earliest (29_______ evidence of beer brewing in China, the researchers reported in the Proceedings of the National Academy of Sciences. To (30)_______ that theory, the team examined the yellowish, dried (31)_______ inside the vessels. The majority of the grains, about 80%, were from cereal crops like barley (大麦),and about 10% were bits of roots, (32)_______lily,which would have made the beer sweeter, the scientists say. Barley was an unexpected find: the crop was domesticated in Western Eurasia and didn't become a (33)_______food in central China until about 2,000 years ago, according to the researchers. Based on that timing, they indicate barley may have (34)_______ in the region not as food, but as (35)_______material for beer brewing.