问题详情：
![(2019·*苏高考)AtsometimeinthepastYellowstonemust]( "(2019·*苏高考)AtsometimeinthepastYellowstonemust")
(2019·*苏高考)At some time in the past Yellowstone must ________ (blow) up with a violence far beyond the scale of anything known to humans.
【回答】
have blown 句意：在过去的某个时候，黄石公园一定发生过一场威力很大的*，远远超过了人类已知的任何等级。must have done是对过去发生的动作最有把握的猜测，意思是“一定”。故填have blown。
知识点：虚拟语气与情态动词
题型：阅读填空
