問題詳情：
![(2019·*蘇高考)AtsometimeinthepastYellowstonemust]( "(2019·*蘇高考)AtsometimeinthepastYellowstonemust")
(2019·*蘇高考)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：在過去的某個時候，黃石公園一定發生過一場威力很大的*，遠遠超過了人類已知的任何等級。must have done是對過去發生的動作最有把握的猜測，意思是“一定”。故填have blown。
知識點：虛擬語氣與情態動詞
題型：閱讀填空
