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1£®She is two hours late. What ___ to her?
A£®may have happened B£®should have happened 
C£®can have happened D£®must have happened
2£®He could have helped us, but he ___ from coming in time by a traffic jam.
A£®has been prevented B£®had been prevented 
C£®is prevented  D£®was prevented
3£®My mind wasn’t on what he was saying, so I’m afraid I ___ half of it.
A£®was missing  B£®had missed  
C£®would miss  D£®missed