课时作业(十二)

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1、课时作业（十二）必修3Unit2HealthyeatingI」阅读理解A（2018-银川检测）Crossingyourlegsisanextremelycommonhabit;mostpeopledon'tevennoticethatthey'redoingitwhentheysitdown.Whileyoumayfinditcomfortabletositwithonekneecrossedovertheother,itmightbecausinghealthproblemsthatyouarenotawareof.AstudypublishedinB

2、loodPressureMonitoringstatedthatsittingwithyourlegscrossedcanincreaseyourbloodpressure.Thereasonforthisisthatthebloodinyourlegshastoworkagainstgravitytobepumpedbacktoyourheartandthatcrossingonelegovertheotherincreasesresistance,makingitevenharderforthebloodtocirculate.Thiscausesy

3、ourbodytoincreaseyourbloodpressuretopushthebloodbacktotheheart.Youwon'tfeelanyimmediateeffects,butrepeated,drawn-outincreasesinbloodpressurecancauselong-termhealthissues.So,planningtositforalongperiodoftime?Don'tkeepyourlegscrossed.uCrossingyourlegsatthekneecanalsocausepressureon

4、themajornerveinyourlegthatpassesjustbelowyourkneeandalongtheoutsideofyourleg,"explainsRichardGraves,amedicalexpert.Thispressurecancausenumbnessandtemporaryparalysis（麻痹）ofsomeofthemusclesinyourfootandleg,preventingyoufrombeingabletoraiseyourankle一whatweknowasthat“pins_and_needles"

5、sensation.Whilethefeelingofdiscomfortmayonlylastaminuteortwo,repeatedlycrossingyourlegsuntiltheyfeelnumbcancausepermanentnervedamage・Sonexttimeyousitdown,trytogetyourselfinthehabitofsittingwithbothofyourfeetonthefloor.Notonlywillithelpyourpostureandstability,butitwillalsosaveyour

6、healthinthelongrun.【文章大意】本文是一篇说明文。文章介绍了人们将一条腿放在另一条腿上（跷二郎腿）的习惯，这种行为会导致一些健康问题。【难句分析】Thereasonforthisisthatthebloodinyourlegshastoworkagainstgravitytobepumpedbacktoyourheartandthatcrossingonelegovertheotherincreasesresistance,makingitevenharderforthebloodtocirculate.（第二段第二句）分析：本句是一个

7、主从复合句。两个that引导的都是表语从句，umakingit...tocirculate为现在分词短语作结果状语。译文：这是因为腿部的血液要回流到心脏，就要与重力对抗，并且把一条腿放在另一条腿上会加剧这种对抗，这使得血液循环更难To1・Whatcanwelearnaboutcrossingone'slegs?A.Itisaverybadsocialhabit,B•Itcandoharmtopeople'shealth・C・Itisusuallypracticeddeliberately.D・Itcanmakeothersfeeluncomfortabl

8、e・答案与解析：B，考查细节理解。根据文章前三段内容可知，人们将一条腿放在另一条