Photoshop中Ctrl+T是自由变换的快捷键，在有一个选区的情况下，按Ctrl+T键必须依靠快捷键才能够完成下列哪些变换操作。()

使用过渡功能制作动画时：

帷幕灌浆，表层孔段的灌浆压力不宜小于（）倍帷幕的工作水头。

Thefoodweeatseemstohaveprofoundeffectsonourhealth.Althoughsciencehasmadeenormousstepsinmakingfoodmorefittoeat,ithas,atthesametime,mademanyfoodsunfittoeat.Someresearchhasshownthatperhapseightypercentofcancerisrelatedtothedietaswell,especiallycancerthecolon.Differentculturesaremorepronetocontractcertainillnessesbecauseofthefoodthatischaracteristicinthesecultures.Thatfoodrelatedtollnessisnotanewdiscovery.In1945,governmentresearchersrealizedthatitratesandnitrites,commonlyusedtopreservecolorinmeats,andotherfooddditives,causedcancer.Yet,thesecarcinogenicadditivesremaininourfood,nditbecomesmoredifficultallthetimetoknowwhichthingsonthepackginglabelsofprocessedfoodarehelpfulorharmful.Theadditiveswhichweeatarenotallsodirect.Farmersoftengivepenicillintobeefandpoultry,andbecauseofthis,penicillinhasbeenfoundinthemilkoftreatedcows.Sometimessimilardrugsareadministeredtoanimalsnotformedicinalpurposes,butforfinancialreasons.Thefarmersaresimplytryingtofattentheanimalsinordertoobtainahigherpriceonthemarket.AlthoughtheFoodandDrugAdministration(FDA)hastriedrepeatedlytocontroltheseprocedures,thepracticescontinue.

48.Whatisthemaintopicofthepassage?

A.Foodandourhealth

BFoodandadditives

C.Foodandcancer

DFoodandculture

49AllofthefollowingstatementsaretrueEXCEPT_______.

AFortypercentofcanceriscausedbyproblemsrelatedtofood.

BResearchershaveknownaboutthepotentialdangeroffoodadditivesformanyyears

C.Weeatsomeofthefoodadditivesdirectlyandsomeindirectly

DDrugsarealwaysgiventoanimalsformedicinalpurposes

50.Whydofarmersgivedrugstotheiranimals?

A.tospeedupthegrowthofanimals

BTomaketheanimalsfatter

Ctomaketheanimals’meatfittoeat

DTomaketheanimals’meatrichinnutrients

51.Itcanbeinferredfromthepassagethat_________.

Ascientisthavemadeallthefoodfittoeat

Bonlyinrecentyearshavepeoplefoundthatthefoodisrelatedtoone’sillness

Callkindsofcancerarerelatedtothediet

Dsomeadditivesareharmfultoourhealth

52.Theword“this”inthesecondsentenceofparagraph2mostprobablyrefersto__________.

Afarmer

Bpenicillin

Cbeefandpoultry

Dthefactthatfarmersoftengivepenicillintoabeef

粉状或颗粒状材料在某堆积体积内，颗粒之间的空隙体积所占的比例称为材料的()。