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Most adults do not get enough fiber in their daily diet. Only 5% of adults meet the recommended daily ___1___ — 25 grams for women under 50 and 38 grams for men. The average person eats only about 17 grams per day.

Fiber is not ___2___ by our bodies directly. Our stomach and small intestine (肠) absorb most nutrients from food, but they ___3___ the enzymes (酶) needed to break down fiber. Instead, fiber passes through to the large intestine, where billions of ___4___ live. These bacteria have genes that allow them to digest fiber, turning it into ___5___ that lower inflammation and help ___6___ us from diseases like type 2 diabetes, heart disease, and certain cancers. Without enough fiber, these bacteria cannot function ___7___, leading to ___8___ and other health issues.

Experts recommend increasing fiber ___9___ gradually rather than all at once. Small changes can make a big difference. For example, ___10___ from white bread to whole wheat bread, adding berries to breakfast cereal, or snacking on nuts instead of processed foods can help ___11___ fiber consumption. Drinking plenty of water along with high-fiber foods is also important, as fiber needs water to work ___12___.

The best sources of fiber are ___13___ plant foods rather than supplements. In whole foods, fiber works together with other nutrients to support digestion, ___14___ supplements often contain only ___15___ fiber types that may not provide the same benefits. While it is possible to take fiber supplements, experts agree that getting fiber from natural food sources is the healthier choice.

1.1.

A score

B limit

C amount

D level

解析：选C。C 考查名词（语境理解）。破折号后25 grams...38 grams是具体数值，可推断前文为推荐的每日摄入量。recommended daily amount为固定搭配。A.score（分数）、B.limit（限制）、D.level（水平）均不能与破折号后的具体克数匹配。故选C。

2.2.

A digested

B created

C collected

D accepted

解析：选A。A 考查动词（语境理解+被动语态）。Fiber is not ___ by our bodies为被动语态，后文break down fiber提示此处指纤维被消化。B.created（创造）、C.collected（收集）、D.accepted（接受）均与下文break down无关。故选A。

3.3.

A lack

B need

C control

D produce

解析：选A。A 考查动词（转折逻辑）。absorb most nutrients... but they ___ the enzymes needed to break down fiber, but表转折：能吸收营养，但缺少分解纤维的酶。B.need（需要）无法构成明确的转折关系；C.control（控制）与酶的功能不匹配；D.produce（产生）与转折矛盾。故选A。

4.4.

A insects

B viruses

C cells

D bacteria

解析：选D。D 考查名词（同义复现）。下句These bacteria直接复现,说明此处是细菌。A.insects（昆虫）、B.viruses（病毒）、C.cells（细胞）均与下文These bacteria不构成同指关系。故选D。

5.5.

A designs

B questions

C substances

D memories

解析：选C。C考查名词（语境理解）。that引导定语从句that lower inflammation修饰先行词，能降低炎症的应是细菌产生的物质。A.designs（设计）、B.questions（问题）、D.memories（记忆）均无法执行降低炎症的功能。故选C。

6.6.

A struggle

B protect

C compete

D fight

解析：选B。B 考查动词（固定搭配）。___ us from diseases中，protect...from为固定搭配，意为保护...免受疾病侵害。A.struggle不与from搭配；C.compete不与from搭配；D.fight不与from搭配。故选B。

7.7.

A bravely

B gently

C loudly

D properly

解析：选D。D 考查副词（语境理解）。Without enough fiber, these bacteria cannot function ___，缺乏纤维时细菌无法正常工作。A.bravely（勇敢地）、B.gently（温柔地）、C.loudly（大声地）均不可修饰function。故选D。

8.8.

A satisfaction

B discomfort

C excitement

D confidence

解析：选B。B 考查名词（语境理解+并列关系）。leading to ___ and other health issues，and连接的是与健康问题并列的负面结果，不适最符合。A.satisfaction（满意）、C.excitement（兴奋）、

9.9.

A quality

B weight

C price

D intake

解析：选D。D 考查名词（搭配+语境）。increasing fiber ___中，fiber intake（纤维摄入量）为常见搭配，与后文Small changes can make a big difference呼应。A.quality（质量）、B.weight（重量）、C.price（价格）均不与fiber构成常见搭配。故选D。

10.10.

A suffering

B switching

C hearing

D learning

解析：选B。B 考查动词（搭配+举例）。___ from white bread to whole wheat bread，switch from...to...为固定搭配，意为从...转成...，且该句为Small changes的举例之一。A.suffering（遭受）、C.hearing（听）、D.learning（学习）均不与from...to...构成此语义。故选B。

11.11.

A limit

B avoid

C boost

D reduce

解析：选C。C 考查动词（语境理解）。前文讨论如何增加纤维摄入，help ___ fiber consumption意为帮助提高纤维摄入。A.limit（限制）、B.avoid（避免）、D.reduce（减少）均与增加摄入的全文主旨矛盾。故选C。

12.12.

A effectively

B formally

C smoothly

D carelessly

解析：选A。A 考查副词（语境理解）。fiber needs water to work ___，纤维需要水才能有效工作。B.formally（正式地）、C.smoothly（平滑地）、D.carelessly（粗心地）均不符合语境。故选A。

13.13.

A whole

B mixed

C fresh

D cooked

解析：选A。A 考查形容词（固定搭配+复现）。___ plant foods中，whole plant foods（全植物食物）是营养学术语，且下句In whole foods直接复现。B.mixed（混合的）、C.fresh（新鲜的）、D.cooked（煮熟的）虽可搭配但无下文呼应。故选A。

14.14.

A because

B whereas

C although

D unless

解析：选B。B 考查连词（对比逻辑）。...works together... ___ supplements often contain only...，前后为对比关系（全食物协同作用vs补充剂只含孤立成分），whereas（然而）表对比。A.because（因为）表因果；C.although（虽然）表让步；D.unless（除非）表条件，均不能准确表达对比。故选B。

15.15.

A different

B natural

C isolated

D similar

解析：选C。C 考查形容词（语境理解+对比）。only contain ___ fiber types，与前半句works together with other nutrients形成对比——全食物中的纤维与其他营养素协同工作，而补充剂通常只含孤立的纤维类型，缺乏协同作用。A.different（不同的）不与only及对比语境呼应；B.natural（天然的）与语境不符；D.similar（相似的）与对比逻辑矛盾。故选C。