Mywalletisnowheretobefound.I_____itwhenIwasonthebus.
D
must have+done 用于推断过去某个时间肯定发生了的事情。
William has cut his smoking_____to five cigarettes a day.
If he_____the storekeeper ‘s scissors ，he would have forgotten to buy a pair.
He‘s working hard_____.
Hewasvery_____togo，buthehadnochoice.
Hedrovefastandarrivedanhour_____ofschedule.
