C
These summer days, when I take my dog Raja for a walk, he always wants to stop and eat grass. However, ___1___ there are many other grasses nearby, he always ___2___wheatgrass.
I've read that dogs eat grass because they want to vomit(呕吐)or they are having digestive troubles. Raja ___3___ to vomit. He will do anything to keep from vomiting, so that doesn't seem to be the ___4___I feed him pretty wet food, and he ___5___ it very well, with well-formed stools(粪便). Digestive troubles do not seem to apply to Raja either. So I decided to ___6___ a little bit into the ___7___ dog literature to see what I could find.
One recent study approached grass eating in dogs with the hypothesis(假说)that grass may ___8___ digestive distress(痛苦). In that study, the ___9___ fed dogs a diet that produced loose, watery stools, to mimic(模拟)a condition of a mild digestive upset. They ___10___ fed the dogs a standard diet that produced ___11___stools, and gave the dogs two types of grasses to eat during each experimental condition. The ___12___ were that the dogs ate more grass when they were fed a standard diet than when they ate the diet that ___13___ the digestive upset. So much for that hypothesis.
Then there's vomiting.
I found another ___14___ that looked at whether dogs vomit more when they eat grass. In it, they surveyed 1571 dog owners on the Internet and ___15___ that 79 percent of the dogs ate grass, and of these, only 9 percent were ___16___ before they ate the grass, and 22 percent vomited ___17___ eating the grass. These results show that the vomiting hypothesis doesn't seem to be ___18___ either.So why do dogs eat grass?
Ask yourself that question the next time you___19___a delicious salad. My ___20 ___is...
because it tastes good.
答案：1-5 ABDCB 6-10 AACDD 11-15 ABABC 16-20 BCDCD
These summer days, when I take my dog Raja for a walk, he always wants to stop and eat grass. However, ___1___ there are many other grasses nearby, he always ___2___wheatgrass.
I've read that dogs eat grass because they want to vomit(呕吐)or they are having digestive troubles. Raja ___3___ to vomit. He will do anything to keep from vomiting, so that doesn't seem to be the ___4___I feed him pretty wet food, and he ___5___ it very well, with well-formed stools(粪便). Digestive troubles do not seem to apply to Raja either. So I decided to ___6___ a little bit into the ___7___ dog literature to see what I could find.
One recent study approached grass eating in dogs with the hypothesis(假说)that grass may ___8___ digestive distress(痛苦). In that study, the ___9___ fed dogs a diet that produced loose, watery stools, to mimic(模拟)a condition of a mild digestive upset. They ___10___ fed the dogs a standard diet that produced ___11___stools, and gave the dogs two types of grasses to eat during each experimental condition. The ___12___ were that the dogs ate more grass when they were fed a standard diet than when they ate the diet that ___13___ the digestive upset. So much for that hypothesis.
Then there's vomiting.
I found another ___14___ that looked at whether dogs vomit more when they eat grass. In it, they surveyed 1571 dog owners on the Internet and ___15___ that 79 percent of the dogs ate grass, and of these, only 9 percent were ___16___ before they ate the grass, and 22 percent vomited ___17___ eating the grass. These results show that the vomiting hypothesis doesn't seem to be ___18___ either.So why do dogs eat grass?
Ask yourself that question the next time you___19___a delicious salad. My ___20 ___is...
because it tastes good.
| 1. A.although | B.unless | C.since | D.because |
| 2.A.looks at | B.heads for | C.waits for | D. gives up |
| 3.A.pretends | B.fails | C.stops | D.hates |
| 4.A.concern | B.process | C.answer | D.detail |
| 5.A.mixes | B.digests | C.handles | D.divides |
| 6.A.dig | B.move | C.fall | D.cut |
| 7.A.scientific | B.descriptive | C.imaginative | D.traditional |
| 8.A.send | B.produce | C.reduce | D.further |
| 9.A.owners | B.farmers | C.doctors | D.researchers |
| 10.A.just | B.even | C.thus | D.also |
| 11.A.normal | B.fresh | C.smelly | D.hard |
| 12. A.secrets | B.results | C.solutions | D.ideas |
| 13. A.caused | B.ignored | C.meant | D.treated |
| 14. A.post | B.study料圈 | C.exercise | D.course |
| 15. A.believed | B.checked | C.found | D.expected |
| 16. A.anxious | B.sick | C.hungry | D.sad |
| 17. A.if | B.until | C.after | D.before |
| 18. A.interesting | B.strange | C.impossible | D.reasonable |
| 19. A.discover | B.serve | C.eat | D.cook |
| 20. A.news. | B.argument | C.promise | D.guess |
