he was able to return.this means he ___ 1 could if he wanted to 2 might 3 could have 4 did选择哪一个,及分别说出每个为什么对与错

he was able to return.this means he ___ 1 could if he wanted to 2 might 3 could have 4 did选择哪一个,及分别说出每个为什么对与错
he was able to return.this means he ___ 1 could if he wanted to 2 might 3 could have 4 did
选择哪一个,及分别说出每个为什么对与错

he was able to return.this means he ___ 1 could if he wanted to 2 might 3 could have 4 did选择哪一个,及分别说出每个为什么对与错
4.was able to do sth意思是成功做到了某事,在这里的意思是he succeeded in returning or he managed to return.所以选4.意思是he returned.
不要用情态动词表示可能性或虚拟,呈现事实.

选择3.could have
很明显，这是一个虚拟语气，他本可以回来的。
虚拟语气：could/should/would+have/has done sth. 本可以做什么的，可是没能做。
希望对你有帮助。

1是对的。 只要他愿意，他可以帮到。。。
2。可能
3。可能已经做。。。
4。做了