為幫助考生有效備考2013年職稱英語考試，職稱英語考試網(wǎng)小編整理了職稱英語綜合類a級補全短文練習題，希望對您學習職稱英語有所幫助！

The Spread of Microorganisms

There is scarcely a place on earth which isnaturally free of microorganisms (微生物). 46 . But on external body surfaces, onlining membranes(內(nèi)膜) and inside tubes and organs that are connected with theoutside—such as the mouth, throat, nose, and large intestine(腸)—bothharmless and pathogenic(病原的)microbes(微生物)live in large numbers. 47 . If thesenatural defenses are sound, a person may conceal many microbes without illeffect. However, if his resistance becomes lowered, an infection can result.

Microbes are spread about through an almost infinite variety of means. 48. The more crowded the conditions, the greater the chances of epidemics(流行病)breaking out. 49 .

Although microbes cannot fly, the dust of the air isalive with them. In close quarters the atmosphere is further polluted bybacteria-loaded tiny drops discharged by coughing and even normal conversation.Pathogenic microbes are also spread by rats, mice, flies and mosquitoes. 50 . Inslum areas there is often a combination of crowded conditions and poorsanitation(環(huán)境衛(wèi)生). In addition, many of the inhabitants have lowered resistancebecause of shortage of food and other undesirable unhealthy practices. As aresult, epidemics are likely to begin in these districts.

All civilizedsocieties establish and enforce measures designed to protect the health of theirpopulations. Most of these practices are concerned with preventing the spread ofthe pathogenic organisms

A The atmosphere is a carrier ofmicroorganisms

B One exception is the interior of normal bodytissue

C Microbial growth is further helped by the widespread presence ofdirt and the lack of sunlight

D The body has natural defenses againstthese organisms

E The body has no defenses against these organisms

FThe simplest way is by person-to-person contact

參考答案: A D C B D

編輯推薦：

2012年職稱英語考試真題匯總

2012年職稱英語考試成績查詢匯總

2013年職稱英語考試網(wǎng)絡課堂輔導

2013年職稱英語綜合類詞匯選項練習題匯總

（責任編輯：vstara）

共2頁,當前第1頁  第一頁  前一頁  下一頁