Itisvitalthatthework_______intime.
A、isdoneB
这里主语从句中应该用虚拟语气，从句谓语用 should+动词原形的形式， should 可以省略。句意：及时完成这项工作是极其重要的。
Itisvitalthatthework_______intime.
Theprofessorworkedfor7hoursata________.
Duringthepasttwodecades,researchhas________ourknowledgeofdaydreaming.
Robotsdifferfromautomaticmachines________aftercompletionofonespecifictask，theycanbereprogrammedbyacomputertodoanotherone.
Thestudentsarerequiredto________themainideasofthearticleintheirownwords.
