he ____easily swim across this river if he wanted to(could)
amundsen ____reach the south pole before Scott(was able to)
i rang up several times before i ____contact him(was able to)
i ____get these tickets because i was willing to stand in the queue for hours(was able to)
这个问题是不小心发重了的,谁来随便回答一下马上给采纳