have not been able 是什么意思?
完整的应该是have not been able to do sth. 意思是未能作成某件事情 OKWAP Online Service Yunfei
have not been able 的完整形式是have not been able to do sth 是be able to do sth. 的现在完成时的否定式,意思是未能做某事.还应该具体看上下文的意思,应该能作“还不能做某事”讲吧.
答:用be to +动词原形表示职责、义务、意图、约定、可能性等。如: ①You are to be back by nine o'clock.到九点你就得回来。 ...详情>>