1.can / could/be able to
1.My sister met him at the Grand Theater yesterday afternoon, so he couldn’t have attended your lecture.( 否定式表示推测，表达“一定不会---”之意)
Jack can’t have arrived yet, otherwise he would have telephoned me．( 否定式表示推测，表达“一定不会---”之意)
2.Mr Bush is on time for everything. How can it be that he was late for the opening ceremony? ( 疑问句中表示推测，表达“可能---”之意，此处与how连用表示惊疑语气。)
