估计失血量中称重法：失血量=【胎儿娩出后接血敷料湿重g-接血前敷料干重g】/()。

Passage2

Questions6to10arebasedonthefollowingpassage:

Whenaluminumwasfirstproducedaboutahundredandfiftyyearsago,itwassodifficulttoseparateformtheoresinwhichitwasfoundthatitspricewashigherthanthatofgold.Thepriceremainedhighuntilanewprocesswasdiscoveredforrefiningthemetalwiththeaidofelectricityapproximatelythreequartersofacenturylater.Thenewmethodwassomuchcheaperthataluminumbecausepracticalformanypurposes,oneofwhichwasmakingpotsandpans.

Aluminumislightweight,rustproofandeasilyshapedintodifferentforms.Bymixingitwithothermetals,scientistshavebeenabletoproduceavarietyofalloys,someofwhichhavethestrengthofsteelbutweighonlyonethirdasmuch.

Today,theusesofaluminumareinnumerable.Perhapsitsmostimportantuseisintransportation.Aluminumisfoundintheengineofautomobiles,inthehullsofboats.Itisalsousedinmanypartsofairplanes.Infact,thehuge“airbus”planeswouldprobablyneverhavebeenproducedifaluminumdidnotexist.Bymakingvehicleslighterinweightaluminumhasgreatlyreducedtheamountoffuelneededtomovethem,Aluminumisalsobeingusedextensivelyinthebuildingindustryinsomecountries.

Sincealuminumissuchaversatile(多用的)metal,itisfortunatethatbauxite(铝土矿),whichisoneofitschiefsources,isalsooneoftheearth’smostplentifulsubstances.Asthesourceofaluminumisalmostinexhaustible,wecanexpectthatmoreandmoreuseswillbefoundforthisversatilemetal.

6.Thepriceofaluminumwassharplyreducedwhenpeoplediscoveredanewrefiningprocesswiththeaidof.

A.windB.solarenergyC.hydraulicpowerD.electricity

7.Aluminumis.

A.lightweight,rustproofbutnoteasilyshapedintodifferentforms

B.heavyweight,rustproofandeasilyshapedintodifferentforms

C.lightweight,rustproofandeasilyshapedintodifferentforms

D.lightweightandeasilyshapedintodifferentformsbutitiseasytobecomerusty

8.WhichofthefollowingisNOTtrue?

A.Aluminumiswidelyusedintransportation.

B.Aluminumisalsousedinmanypartsofairplanes.

C.Aluminumisbeingusedextensivelyinthebuildingindustry.

D.Aluminumisnotusedinitspureform.

9.Aluminumisfoundonearthmostlyintheformof.

A.puremetalB.bauxiteC.goldD.liquid

10.Whatisthepassagetalkingabout?

A.Thefeaturesofaluminumanditsfunctions.B.Theprocessofaluminum.

C.Thediscoveryofaluminum.D.Thepromisingfutureofaluminum.

分娩时最主要的产力是

关于枕前位分娩机转，下列哪些不正确?

某孕妇，妊娠34周，做胎心监护时为判断基线胎心率，监护时间至少为