When _______, water will be turned into steam.
A
水被加热时会变成蒸汽。因为主句主语water和从句谓语heat的关系是被动的，所以用过去分词。
Ayearlater，withthenation’seconomy________，Bush’sapprovalratingdroppedbelow40percent
Duringthepasttwodecades,researchhas________ourknowledgeofdaydreaming.
Robotsdifferfromautomaticmachines________aftercompletionofonespecifictask，theycanbereprogrammedbyacomputertodoanotherone.
Basically，theseattitudesamounttoabelief________leisurecanandshouldbeputtogooduse