Question

The old man,______abroad for twenty years, is on the way back to his motherland.

填空，填having worked 为什么不能填has worked？

Answer 1

因为这句话的主句是 The old man is on the way back to his motherland.
这句话是个主系表结构，主语是the old man, 谓语动词是Be动词is,
主句已经完整， ,______abroad for twenty years， 空格的地方不能再用谓语动词has worked，只能用成分词做状语哦结构，having worked

如果非要用has worked，
用了的话这句话就一个主语 The old man, 然后有两个谓语动词1： has worked 2, is, 英语中一个简单句中是不可以有两个谓语动词的。

这句话就必须用并列连词说成The old man has worked abroad for twenty years and is on the way back to his motherland, 或者用连词做成状语从句：SInce he has worked abroad for twenty years, the old man is on the way back to his motherland.